OLD NATIONAL BANCORP /IN/
424B1, 2000-03-13
NATIONAL COMMERCIAL BANKS
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<PAGE>   1

PROSPECTUS SUPPLEMENT
(TO PROSPECTUS DATED FEBRUARY 29, 2000)

                         2,000,000 PREFERRED SECURITIES

                              ONB CAPITAL TRUST I
                  9.500% TRUST PREFERRED SECURITIES (TRUPS(R))
              FULLY, IRREVOCABLY AND UNCONDITIONALLY GUARANTEED BY

                              OLD NATIONAL BANCORP

     A brief description of the 9.500% Trust Preferred Securities (TRUPS(R)) can
be found under "Summary Information -- Q&A" in this prospectus supplement.
                           -------------------------

     Application will be made to list the 9.500% Trust Preferred Securities
(TRUPS(R)) on the New York Stock Exchange. If approved, Old National Bancorp
expects trading of the 9.500% Trust Preferred Securities (TRUPS(R)) to begin
within 30 days after they are first issued.

     INVESTING IN THE 9.500% TRUST PREFERRED SECURITIES (TRUPS(R)) INVOLVES
RISK. SEE "RISK FACTORS" BEGINNING ON PAGE S-6.

     Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or determined if this
prospectus supplement or the accompanying prospectus is truthful or complete.
Any representation to the contrary is a criminal offense.

     These securities are not deposits or savings accounts. These securities are
not insured by the Federal Deposit Insurance Corporation or any other
governmental agency or instrumentality.
                           -------------------------

<TABLE>
<CAPTION>
                                                                   PER TRUST
                                                               PREFERRED SECURITY           TOTAL
                                                               ------------------           -----
<S>                                                          <C>                    <C>
Public offering price.......................................         $25.00              $50,000,000
Underwriting commissions to be paid by Old National
  Bancorp...................................................       See below.             See below.
Proceeds to ONB Capital Trust I.............................         $25.00              $50,000,000
</TABLE>

                           -------------------------

     Underwriting commissions of $0.7875 per 9.500% Trust Preferred Security (or
$1,575,000 for all 9.500% Trust Preferred Securities (TRUPS(R))) will be paid by
Old National Bancorp.

     Old National Bancorp expects that the 9.500% Trust Preferred Securities
(TRUPS(R)) will be ready for delivery in book-entry form only through The
Depository Trust Company on or about March 14, 2000.

     "TRUPS(R)" is a registered service mark of Salomon Smith Barney Inc.
                           -------------------------

SALOMON SMITH BARNEY
            MERRILL LYNCH & CO.
                         PAINEWEBBER INCORPORATED
                                    PRUDENTIAL SECURITIES
                                             STIFEL, NICOLAUS & COMPANY
                                                        INCORPORATED
March 9, 2000
<PAGE>   2

                               TABLE OF CONTENTS

                             PROSPECTUS SUPPLEMENT

<TABLE>
<CAPTION>
                                                               PAGE
                                                               ----
<S>                                                            <C>
Summary Information -- Q&A..................................    S-3
Risk Factors................................................    S-6
Cautionary Statements.......................................    S-9
Use of Proceeds.............................................    S-9
Selected Financial Data.....................................   S-10
Recent Developments.........................................   S-11
Accounting Treatment........................................   S-13
Description of Securities...................................   S-13
Certain Terms of the Preferred Securities...................   S-14
Certain Terms of the Junior Subordinated Debentures.........   S-15
United States Federal Income Taxation.......................   S-16
ERISA Considerations........................................   S-21
Underwriting................................................   S-23
Legal Matters...............................................   S-24
</TABLE>

                                   PROSPECTUS

<TABLE>
<S>                                                            <C>
About this Prospectus.......................................     2
Forward-Looking Statements and Cautionary Factors...........     2
Where You Can Find More Information.........................     3
Old National Bancorp........................................     4
The ONB Trusts..............................................     5
Use of Proceeds.............................................     6
Capitalization..............................................     7
Ratio of Earnings to Fixed Charges..........................     7
Description of Debt Securities..............................     7
Description of Capital Securities...........................    18
Description of Guarantees...................................    28
Relationship Among the Capital Securities, the Corresponding
  Junior Subordinated Debentures and the Guarantees.........    31
Book-Entry Issuance.........................................    32
Underwriting................................................    35
Certain Legal Matters.......................................    36
Experts.....................................................    37
</TABLE>

                                       S-2
<PAGE>   3

                            SUMMARY INFORMATION-Q&A

     The following information supplements, and should be read together with,
the information contained in other parts of this prospectus supplement and in
the accompanying prospectus. This summary highlights selected information from
this prospectus supplement and the accompanying prospectus to help you
understand the preferred securities. You should carefully read this prospectus
supplement and the accompanying prospectus to understand fully the terms of the
preferred securities as well as the tax and other considerations that are
important to you in making a decision about whether to invest in the preferred
securities. You should pay special attention to the "Risk Factors" section
beginning on page S-6 of this prospectus supplement to determine whether an
investment in the preferred securities is appropriate for you.

WHAT ARE THE PREFERRED SECURITIES?

     Each preferred security represents an undivided beneficial interest in the
assets of ONB Capital Trust I. Each preferred security will entitle the holder
to receive quarterly cash distributions as described in this prospectus
supplement. ONB Capital Trust I is offering 2,000,000 preferred securities at a
price of $25.00 for each preferred security.

WHO IS ONB CAPITAL TRUST I?

     ONB Capital Trust I will sell its preferred securities to the public and
its common securities to Old National Bancorp. ONB Capital Trust I will use the
proceeds from these sales to buy from Old National a series of 9.5000% junior
subordinated debentures due March 15, 2030, with the same financial terms as the
preferred securities. Old National will guarantee payments made on the preferred
securities as described below.

     The principal place of business of ONB Capital Trust I is c/o Old National
Bancorp, 420 Main Street, Evansville, Indiana 47708. Its telephone number is
(812) 464-1434.

     Bank One Trust Company, NA will act as property trustee of ONB Capital
Trust I. Bank One Delaware, Inc. will be the Delaware trustee. Bank One Trust
Company, NA will act as trustee under the indenture pursuant to which the junior
subordinated debentures will be issued and will act as trustee under the
guarantee of Old National. The property trustee and Delaware trustee are
sometimes referred to as the issuer trustees. In addition, two officers,
employees or affiliates of Old National will act as administrators of ONB
Capital Trust I.

WHO IS OLD NATIONAL?

     Old National is a bank holding company. Old National currently operates 124
banking offices in Indiana, Illinois, Kentucky and Tennessee. Old National also
owns non-bank subsidiaries that provide fiduciary, trust, securities brokerage,
investment, insurance agency and consumer finance services. Old National's
principal office is at 420 Main Street, Evansville, Indiana 47708. Old
National's telephone number is (812) 464-1434. See "Old National Bancorp" in the
accompanying prospectus.

WHEN WILL YOU RECEIVE QUARTERLY DISTRIBUTIONS?

     If you purchase the preferred securities, you are entitled to receive
cumulative cash distributions at an annual rate of 9.5000% of the liquidation
amount of $25 per preferred security. Distributions will accumulate from the
date ONB Capital Trust I issues the preferred securities and will be paid
quarterly in arrears on March 30, June 30, September 30 and December 30 of each
year, beginning June 30, 2000.

     ONB Capital Trust I's only source of cash to make distributions on the
preferred securities is the quarterly payments ONB Capital Trust I will receive
on the junior subordinated debentures it purchases from Old National.

                                       S-3
<PAGE>   4

WHEN CAN PAYMENT OF YOUR DISTRIBUTIONS BE DEFERRED?

     So long as no event of default under the junior subordinated debentures has
occurred and is continuing, Old National may, on one or more occasions, defer
interest payments on the junior subordinated debentures for up to 20 consecutive
quarterly periods. A deferral of interest payments cannot extend, however,
beyond the maturity date of the junior subordinated debentures, which is March
15, 2030.

     If Old National defers interest payments on the junior subordinated
debentures, ONB Capital Trust I will also defer distributions on the preferred
securities. During this deferral period, distributions will continue to accrue
on the preferred securities at an annual rate of 9.500% of the liquidation
amount of $25 per preferred security. Also, the deferred distributions will
themselves accrue interest at an annual rate of 9.500% to the extent permitted
by law. Once Old National makes all interest payments on the junior subordinated
debentures, with accrued interest, it can again defer interest payments on the
junior subordinated debentures if no event of default under the junior
subordinated debentures has occurred and is continuing.

     During any period in which Old National defers interest payments on the
junior subordinated debentures, with limited exceptions, Old National will not
be permitted to:

     - pay a dividend or make any distributions on its capital stock or redeem,
       purchase, acquire or make a liquidation payment on any of its capital
       stock, or make any guarantee payments with respect to the foregoing; or

     - make an interest, principal or premium payment on, or repay, repurchase
       or redeem, any of Old National's debt securities that rank equal or
       junior to the junior subordinated debentures.

     If Old National defers payments of interest on the junior subordinated
debentures, the preferred securities will, from the time of the deferral, be
treated as being issued with original issue discount for United States federal
income tax purposes. This means you will be required to recognize interest
income with respect to distributions and include those amounts in your gross
income for United States federal income tax purposes even though you will not
have received any cash distributions relating to that interest income. See
"United States Federal Income Taxation -- Interest Income and Original Issue
Discount."

WHEN CAN ONB CAPITAL TRUST I REDEEM THE PREFERRED SECURITIES?

     ONB Capital Trust I must redeem all of the outstanding preferred securities
and common securities when the junior subordinated debentures are paid at
maturity on March 15, 2030. In addition, if Old National redeems any junior
subordinated debentures before their maturity date, ONB Capital Trust I will use
the cash it receives from that redemption to redeem, on a pro rata basis,
preferred securities and common securities having a combined liquidation amount
equal to the principal amount of the junior subordinated debentures redeemed.

     Old National can redeem some or all of the junior subordinated debentures
before their maturity at a redemption price equal to $25 per junior subordinated
debenture plus accrued and unpaid distributions to the date of redemption on one
or more occasions at any time on or after March 15, 2005. Old National also has
the option to redeem the junior subordinated debentures, in whole, but not in
part, at any time if certain changes in tax, investment company or bank
regulatory law occur and other specified conditions are satisfied, as more fully
described under "Certain Terms of the Preferred Securities -- Redemption --
Special Event Redemption." In that case, the redemption price will be equal to
$25 per preferred security plus accrued and unpaid distributions to the date of
redemption. Prior to any redemption, Old National will obtain any required
regulatory approvals.

                                       S-4
<PAGE>   5

WHAT IS OLD NATIONAL'S GUARANTEE OF THE PREFERRED SECURITIES?

     Old National's guarantee of the distributions on the preferred securities
will be based on:

     - its obligations to make payments on the junior subordinated debentures;

     - its obligations under the guarantee; and

     - its obligations under the trust agreement of ONB Capital Trust I.

     Old National has irrevocably guaranteed that if a payment on the junior
subordinated debentures is made to ONB Capital Trust I but, for any reason, ONB
Capital Trust I does not make the corresponding distribution or redemption
payment to the holders of the preferred securities, then Old National will make
the payments directly to the holders of the preferred securities. To avoid a
double payment to a holder of the preferred securities, if Old National makes a
payment under the guarantee, the holder will no longer have a right to receive
the corresponding payment from ONB Capital Trust I.

     The payment of distributions on the preferred securities is guaranteed by
Old National under the guarantee only to the extent ONB Capital Trust I has
funds legally and immediately available to make distributions.

     Old National's obligations under the guarantee are subordinated as
described on page 31 of the accompanying prospectus.

WHEN COULD THE JUNIOR SUBORDINATED DEBENTURES BE DISTRIBUTED TO YOU?

     Old National has the right to terminate ONB Capital Trust I at any time. If
Old National terminates ONB Capital Trust I, ONB Capital Trust I, after
satisfaction of any liabilities to its creditors as provided by applicable law,
will liquidate by distributing the junior subordinated debentures to holders of
the preferred securities and the common securities on a pro rata basis. If the
junior subordinated debentures are distributed, Old National will use its best
efforts to list the junior subordinated debentures on the New York Stock
Exchange (or any other exchange on which the preferred securities are then
listed) in place of the preferred securities.

WILL THE PREFERRED SECURITIES BE LISTED ON A STOCK EXCHANGE?

     Application will be made to list the preferred securities on the New York
Stock Exchange. If approved, trading of the preferred securities is expected to
begin within 30 days after they are first issued.

WILL HOLDERS OF THE PREFERRED SECURITIES HAVE ANY VOTING RIGHTS?

     Generally, the holders of the preferred securities will not have any voting
rights. See "Description of Capital Securities -- Voting Rights; Amendment of
Each Trust Agreement" in the accompanying prospectus.

IN WHAT FORM WILL THE PREFERRED SECURITIES BE ISSUED?

     The preferred securities will be represented by one or more global
securities that will be deposited with and registered in the name of The
Depository Trust Company or its nominee. This means that you will not receive a
certificate for your preferred securities and that your broker will maintain
your position in the preferred securities. Old National expects that the
preferred securities will be ready for delivery through DTC on or about March
14, 2000.

                                       S-5
<PAGE>   6

                                  RISK FACTORS

     Your investment in the preferred securities will involve certain risks. You
should carefully consider the following discussion of risks, and the other
information in this prospectus supplement and the accompanying prospectus,
including documents incorporated by reference in the prospectus, before deciding
whether an investment in the preferred securities is suitable for you.

OLD NATIONAL'S OBLIGATIONS UNDER THE JUNIOR SUBORDINATED DEBENTURES AND THE
GUARANTEE ARE DEEPLY SUBORDINATED.

     Old National's obligations under the junior subordinated debentures are
unsecured and will rank junior in priority of payment to all of Old National's
Senior Debt as described on page 10 of the accompanying prospectus. Old
National's obligations under the guarantee will rank in priority of payment as
follows:

     - subordinate and junior in right of payment to all its other liabilities,
       except those that rank equally with or subordinate to the junior
       subordinated debentures by their terms;

     - equally with all other guarantees relating to preferred securities issued
       by any ONB Trust, if any are issued; and

     - senior to its common stock.

     This means that Old National cannot make any payments on the junior
subordinated debentures or the guarantee if it defaults on a payment of Senior
Debt and does not cure the default within the applicable grace period or if the
Senior Debt becomes immediately due because of a default and has not yet been
paid in full. In addition, in the event of the bankruptcy, liquidation or
termination of Old National, its assets would be available to pay obligations
under the guarantee only after Old National made all payments on its Senior
Debt.

     Because Old National is a holding company, dividends and fees from
subsidiaries are Old National's principal source of revenues from which to repay
the junior subordinated debentures. Old National's subsidiaries engaged in the
banking, insurance or securities business can only pay dividends if they are in
compliance with applicable U.S. federal and state regulatory requirements. Old
National's right to participate in any asset distribution of any of its
subsidiaries, on liquidation, reorganization or otherwise, will rank junior to
the rights of all creditors of that subsidiary, except to the extent that Old
National may itself be a creditor of that subsidiary. The rights of holders of
the preferred securities or junior subordinated debentures to benefit from those
distributions will also be junior to those prior claims. Consequently, the
junior subordinated debentures and, therefore, the preferred securities will be
effectively subordinated to all liabilities of Old National's subsidiaries. You
should look only to the assets of Old National for payments on the junior
subordinated debentures and, consequently, the preferred securities.

     At September 30, 1999, Old National had total liabilities of approximately
$6.4 billion, all of which effectively ranks senior to the junior subordinated
debentures.

     None of the preferred securities, the junior subordinated debentures nor
the guarantee limit the ability of Old National or its subsidiaries to incur
additional debts, including debts that rank senior in priority of payment to the
junior subordinated debentures and the guarantee. See "Description of
Guarantees -- Status of the Guarantees" and "Description of Debt Securities" in
the accompanying prospectus.

THE GUARANTEE ONLY COVERS PAYMENTS IF ONB CAPITAL TRUST I HAS CASH AVAILABLE,
BUT YOU MAY SUE OLD NATIONAL DIRECTLY.

     The ability of ONB Capital Trust I to pay scheduled distributions on the
preferred securities, the redemption price of the preferred securities and the
liquidation amount of each preferred security is solely dependent upon Old
National making the related payments on the junior subordinated debentures when
due.

                                       S-6
<PAGE>   7

     If Old National defaults on its obligations to pay principal or interest on
the junior subordinated debentures, ONB Capital Trust I will not have sufficient
funds to pay distributions, the redemption price or the liquidation amount of
each preferred security. In those circumstances, you will not be able to rely
upon the guarantee for payment of these amounts.

     Instead, you:

     - may directly sue Old National or seek other remedies to collect your pro
       rata share of payments owed; or

     - may rely on the property trustee to enforce ONB Capital Trust I's rights
       against Old National under the junior subordinated debentures.

DEFERRAL OF DISTRIBUTIONS WOULD HAVE TAX CONSEQUENCES FOR YOU AND MAY AFFECT THE
TRADING PRICE OF THE PREFERRED SECURITIES.

     So long as no event of default under the junior subordinated debentures has
occurred and is continuing, Old National may, on one or more occasions, defer
interest payments on the junior subordinated debentures for up to 20 consecutive
quarterly periods. If Old National defers interest payments on the junior
subordinated debentures, ONB Capital Trust I will defer distributions on the
preferred securities during any deferral period. However, distributions would
still accumulate and the deferred distributions would themselves accrue interest
at the rate of 9.500% per annum, to the extent permitted by law.

     If Old National defers interest payments on the junior subordinated
debentures, you will be required to recognize interest income in your gross
income for United States federal income tax purposes in the form of original
issue discount, based on your pro rata share of the accrued interest on the
junior subordinated debentures held by ONB Capital Trust I, before you receive
any cash relating to that interest. In addition, you will not receive the cash
if you sell the preferred securities before the end of any deferral period or
before the record date relating to distributions that are paid.

     Old National has no current intention of deferring interest payments on the
junior subordinated debentures. However, if Old National exercises its deferral
right in the future, the preferred securities may trade at a price that does not
fully reflect the value of accrued but unpaid interest on the junior
subordinated debentures. If you sell the preferred securities during an interest
deferral period, you may not receive the same return on investment as someone
else who continues to hold the preferred securities. In addition, because the
preferred securities represent an undivided beneficial interest in ONB Capital
Trust I, substantially all of the assets of which consist of the junior
subordinated debentures, the existence of Old National's right to defer payments
of interest on the junior subordinated debentures may mean that the market price
for the preferred securities may be more volatile than other securities that do
not have these rights.

     See "United States Federal Income Taxation" for more information regarding
the tax consequences of purchasing, holding and selling the preferred
securities.

YOU SHOULD NOT RELY ON DISTRIBUTIONS FROM THE PREFERRED SECURITIES THROUGH THE
MATURITY DATE OF THE JUNIOR SUBORDINATED DEBENTURES -- THE JUNIOR SUBORDINATED
DEBENTURES, AND CONSEQUENTLY, THE PREFERRED SECURITIES, MAY BE REDEEMED AT ANY
TIME IF SPECIFIED CHANGES IN TAX, INVESTMENT COMPANY OR BANK REGULATORY LAW
OCCUR.

     If certain changes in tax, investment company or bank regulatory law occur
and are continuing, and other conditions are satisfied, the junior subordinated
debentures may be redeemed by Old National, in whole but not in part, at any
time within 90 days of the event at a redemption price equal to $25 per junior
subordinated debenture plus any accrued and unpaid interest payments to the
redemption date. Any such redemption will cause a mandatory redemption of
preferred securities and common securities having an aggregate liquidation
amount equal to the aggregate principal amount of the junior subordinated
debentures redeemed. Prior to any such redemption, Old National will obtain any
required regulatory
                                       S-7
<PAGE>   8

approvals. See "Description of Debt Securities -- Certain Provisions Relating to
Junior Subordinated Debentures Issued to the ONB Trusts -- Redemption" and
"Description of Preferred Securities -- Redemption or Exchange" in the
accompanying prospectus.

YOU SHOULD NOT RELY ON DISTRIBUTIONS FROM THE PREFERRED SECURITIES THROUGH THE
MATURITY DATE OF THE JUNIOR SUBORDINATED DEBENTURES -- THE JUNIOR SUBORDINATED
DEBENTURES AND, CONSEQUENTLY, THE PREFERRED SECURITIES, MAY BE REDEEMED AT THE
OPTION OF OLD NATIONAL AS EARLY AS FIVE YEARS AFTER ISSUANCE.

     At the option of Old National, on or after March 15, 2005, the junior
subordinated debentures may be redeemed, in whole, at any time, or in part, from
time to time, at a redemption price equal to $25 per junior subordinated
debenture plus any accrued and unpaid interest payments to the redemption date.
See "Certain Terms of the Junior Subordinated Debentures -- Redemption." Prior
to any such redemption, Old National will obtain any required regulatory
approvals. You should assume that Old National will exercise its redemption
option if Old National is able to refinance at a lower interest rate or it is
otherwise in Old National's interest to redeem the junior subordinated
debentures. If the junior subordinated debentures are redeemed, ONB Capital
Trust I must redeem the preferred securities and the common securities having an
aggregate liquidation amount equal to the aggregate principal amount of junior
subordinated debentures redeemed. See "Description of Capital
Securities -- Redemption or Exchange" in the accompanying prospectus.

OLD NATIONAL MAY TERMINATE ONB CAPITAL TRUST I AT ANY TIME.

     Old National has the right to terminate ONB Capital Trust I at any time, so
long as it obtains any required regulatory approval. If Old National decides to
exercise its right to terminate ONB Capital Trust I, ONB Capital Trust I, after
satisfaction of any liabilities to its creditors as provided by applicable law,
will liquidate by distributing the junior subordinated debentures to holders of
the preferred securities and the common securities on a pro rata basis. Under
current law, such a distribution would not be a taxable event for United States
federal income tax purposes.

     Old National has no current intention of causing the termination of ONB
Capital Trust I and the distribution of the junior subordinated debentures. Old
National anticipates that it would consider exercising this right in the event
that expenses associated with maintaining ONB Capital Trust I were substantially
greater than currently expected, for example if unfavorable changes in tax law
or investment company law occur. See "Description of Debt Securities -- Certain
Provisions Relating to Junior Subordinated Debentures Issued to the ONB
Trusts -- Redemption" in the accompanying prospectus. Old National cannot
predict the other circumstances under which this right would be exercised.

THERE CAN BE NO ASSURANCE AS TO THE MARKET PRICES FOR THE PREFERRED SECURITIES
OR THE JUNIOR SUBORDINATED DEBENTURES; THEREFORE, YOU MAY SUFFER A LOSS.

     Old National and ONB Capital Trust I cannot give you any assurance as to
the market prices for the preferred securities or the junior subordinated
debentures distributed to you upon the termination of ONB Capital Trust I.
Accordingly, the preferred securities that an investor may purchase, whether
pursuant to the offer made by this prospectus supplement or in the secondary
market, or the junior subordinated debentures that a holder of preferred
securities would receive upon a termination of ONB Capital Trust I, may trade at
a discount to the price that the investor paid to purchase the preferred
securities offered by this prospectus supplement. As a result of Old National's
right to defer interest payments on the junior subordinated debentures, the
market price of the preferred securities, which represent undivided beneficial
ownership interests in ONB Capital Trust I, substantially all of the assets of
which consist of the junior subordinated debentures, may be more volatile than
the market prices of other securities that are not subject to similar optional
deferrals.

     Under current United States federal income tax law, a distribution of
junior subordinated debentures to you on the termination of ONB Capital Trust I
should not be a taxable event to you. However, if ONB Capital Trust I is
characterized for United States federal income tax purposes as an association

                                       S-8
<PAGE>   9

taxable as a corporation at the time it is terminated or if there is a change in
law, the distribution of junior subordinated debentures to you may be a taxable
event to you.

THERE MAY BE NO TRADING MARKET FOR THE PREFERRED SECURITIES.

     Before this offering there has been no market for the preferred securities.
Although Old National has applied to list the preferred securities on the New
York Stock Exchange, a listing does not guarantee that a trading market for the
preferred securities will develop, or, if a trading market does develop, the
depth of that market or the ability of the holders to easily sell their
preferred securities.

YOU HAVE VOTING RIGHTS ONLY UNDER LIMITED CIRCUMSTANCES.

     You will have limited voting rights. In particular, subject to certain
exceptions, only Old National can appoint or remove any of the issuer trustees.
See "Description of Capital Securities -- Voting Rights; Amendment of Each Trust
Agreement" in the accompanying prospectus.

                             CAUTIONARY STATEMENTS

     You should rely only on the information contained or incorporated by
reference in this prospectus supplement and the accompanying prospectus. Old
National has not, and the underwriters have not, authorized any other person to
provide you with different information. If anyone provides you with different or
inconsistent information, you should not rely on it. Old National is not, and
the underwriters are not, making an offer to sell these securities in any
jurisdiction where the offer or sale is not permitted. You should assume that
the information appearing in this prospectus supplement and the accompanying
prospectus is accurate as of the date on the front of this prospectus supplement
only. Old National's business, financial condition, results of operations and
prospects may have changed since that date.

                                USE OF PROCEEDS

     ONB Capital Trust I will use all of the proceeds it receives from the sale
of its preferred securities and common securities to purchase junior
subordinated debentures from Old National. Old National intends to use the
proceeds from the sale of the junior subordinated debt securities to ONB Capital
Trust I for repurchases of its common stock in connection with its announced
stock repurchase program, repayment of debt and general corporate purposes,
including possible future acquisitions. Old National may temporarily invest any
funds not required immediately for those purposes in short-term marketable
securities.

                                       S-9
<PAGE>   10

                            SELECTED FINANCIAL DATA

SUMMARY FINANCIAL DATA

     The following financial data are derived from the consolidated financial
statements of Old National. This information should be read in conjunction with,
and is qualified by reference to, the more detailed information contained in the
consolidated financial statements and the accompanying notes thereto
incorporated by reference in this prospectus. See "Where You Can Find More
Information" in the accompanying prospectus.

<TABLE>
<CAPTION>
                                       NINE MONTHS ENDED
                                         SEPTEMBER 30,                               YEAR ENDED DECEMBER 31,
                                 -----------------------------   ----------------------------------------------------------------
                                     1999            1998           1998         1997          1996          1995         1994
                                 -------------   -------------   ----------   ----------   ------------   ----------   ----------
                                                              ($ IN THOUSANDS EXCEPT PER SHARE DATA)
<S>                              <C>             <C>             <C>          <C>          <C>            <C>          <C>
RESULTS OF OPERATIONS
  (Taxable equivalent basis)
  Interest income..............   $  374,906      $  351,426     $  470,915   $  448,875    $  419,483    $  402,793   $  353,983
  Interest expense.............      183,723         172,930        231,613      216,868       196,289       191,835      149,809
                                  ----------      ----------     ----------   ----------    ----------    ----------   ----------
  Net interest income..........      191,183         178,496        239,302      232,007       223,194       210,958      204,174
  Provision for loan losses....        8,437           9,189         12,160       13,562        11,082         7,491        7,886
                                  ----------      ----------     ----------   ----------    ----------    ----------   ----------
  Net interest income after
    provision for loan
    losses.....................      182,746         169,307        227,142      218,445       212,112       203,467      196,288
  Noninterest income...........       50,186          42,879         58,891       51,104        47,402        42,044       36,680
  Noninterest expense..........      134,695         122,442        167,937      158,631       156,720       153,345      152,093
                                  ----------      ----------     ----------   ----------    ----------    ----------   ----------
  Income before income taxes...       98,237          89,744        118,096      110,918       102,794        92,166       80,875
  Income taxes.................       35,389          33,603         43,961       42,835        40,107        35,222       29,550
                                  ----------      ----------     ----------   ----------    ----------    ----------   ----------
  Net income from continuing
    operations.................       62,848          56,141         74,135       68,083        62,687        56,944       51,325
    Discontinued operations....        3,483          (9,854)        (9,854)      (5,005)          494             0           --
                                  ----------      ----------     ----------   ----------    ----------    ----------   ----------
  Net Income...................   $   66,331      $   46,287     $   64,281   $   63,078    $   63,181    $   56,944   $   51,325
                                  ==========      ==========     ==========   ==========    ==========    ==========   ==========
PERIOD-END BALANCES
  Total assets.................   $6,963,307      $6,235,978     $6,416,611   $5,933,321    $5,602,460    $5,281,387   $5,081,088
  Investment securities........    1,725,378       1,611,085      1,636,674    1,606,930     1,573,708     1,481,267    1,458,443
  Loans, net of unearned
    income.....................    4,796,556       4,228,864      4,354,256    3,915,841     3,627,592     3,375,915    3,205,097
  Deposits.....................    5,025,330       4,592,992      4,668,858    4,521,010     4,479,357     4,336,372    4,028,932
  Shareholders' equity.........      514,935         518,083        519,645      500,609       480,435       481,511      457,971
PER SHARE DATA (on continuing
  operations)(1)
  Net income-basic.............   $     1.30      $     1.16     $     1.54   $     1.40    $     1.25    $     1.10   $     0.97
  Net income-diluted(2)........         1.26            1.13           1.49         1.36          1.22          1.08         0.95
  Cash dividends paid..........         0.47            0.42           0.55         0.53          0.50          0.49         0.46
  Book value at year-end.......        10.75           10.76          10.86        10.41          9.77          9.43         8.72
SELECTED PERFORMANCE RATIOS (on
  continuing operations)
  Return on assets.............         1.25%           1.23%          1.21%        1.19%         1.17%         1.11%        1.04%
  Return on equity(3)..........        15.91           15.13          14.95        14.28         13.23         12.20        11.07
  Net Interest Margin..........         4.02            4.19           4.17         4.31          4.42          4.38         4.38
  Average equity to average
    assets.....................         7.91            8.42           8.38         8.46          8.95          9.02         9.36
  Dividend payout..............        36.20%          36.07%         35.15%       36.74%        38.96%        43.90%       47.36%
  Primary capital to assets....         8.73            9.26           9.22         9.27          9.77          9.88        10.26
  Net charge-offs to average
    loans......................         0.09            0.21           0.23         0.21          0.30          0.25         0.27
  End of period allowance for
    loan losses to end of
    period loans...............         1.21            1.23           1.19         1.25          1.20          1.27         1.36
  Non-performing loans to total
    loans......................         0.40%           0.38%          0.45%        0.39%         0.46%         0.29%        0.39%
  Leverage ratio...............         7.51            7.80           7.72         7.95          8.28          8.83         9.13
  Tier 1 capital to risk
    adjusted assets............        11.58           11.58          11.40        12.17         12.90         13.92        14.20
  Efficiency ratio(4)..........        55.03           55.31          56.32        56.03         57.92         60.61        63.15
</TABLE>

- ---------------

(1) Restated for all stock dividends.

(2) Assumes the conversion of Old National's subordinated debentures.

(3) Excludes unrealized gains (losses) on investment securities.

(4) Excludes charter consolidation expenses and security gains (losses). See
    "Recent Developments -- One Bank."

                                      S-10
<PAGE>   11

                              RECENT DEVELOPMENTS

FINANCIAL RESULTS (UNAUDITED)

     For the year ended December 31, 1999, Old National reported income from
continuing operations of $82.69 million. The results for the year represent a
11.5% increase over the previous year.

     At December 31, 1999, Old National reported assets of $6.98 billion, a 8.8%
increase since December 31, 1998, and its shareholders' equity was $492.7
million.

     The following financial data are derived from the unaudited and unpublished
consolidated financial statements of Old National.

<TABLE>
<CAPTION>
                                                               YEAR ENDED
                                                              DECEMBER 31,
                                                                  1999
                                                              ------------
                                                              (UNAUDITED)
<S>                                                           <C>
($ IN THOUSANDS EXCEPT PER SHARE DATA)

RESULTS OF OPERATIONS
(Taxable equivalent basis)
Interest income.............................................   $  505,761
Interest expense............................................      250,536
                                                               ----------
Net interest income.........................................      255,225
Provision for loan losses...................................       11,489
                                                               ----------
Net interest income after provision for loan losses.........      243,736
Noninterest income..........................................       67,508
Noninterest expense.........................................      185,564
                                                               ----------
Income before income taxes..................................      125,680
Income taxes................................................       42,986
                                                               ----------
Net income from continuing operations.......................       82,694
  Discontinued operations...................................        4,101
                                                               ----------
Net Income..................................................   $   86,795
                                                               ==========
PERIOD-END BALANCES
Total assets................................................   $6,982,932
Investment securities.......................................    1,678,651
Loans, net of unearned income...............................    4,837,934
Deposits....................................................    5,071,298
Shareholders' equity........................................      492,744
PER SHARE DATA (on continuing operations)(1)
Net income -- basic.........................................   $     1.72
Net income -- diluted(2)....................................         1.67
Cash dividends paid.........................................         0.63
Book value at year-end......................................        10.42
</TABLE>

                                      S-11
<PAGE>   12

<TABLE>
<CAPTION>
                                                               YEAR ENDED
                                                              DECEMBER 31,
                                                                  1999
                                                              ------------
                                                              (UNAUDITED)
<S>                                                           <C>
SELECTED PERFORMANCE RATIOS (ON CONTINUING OPERATIONS)
Return on assets............................................      1.22%
Return on equity(3).........................................     15.70
Net Interest Margin.........................................      4.00
Average equity to average assets............................      7.75
Dividend payout.............................................     36.95
Primary capital to assets...................................      8.57
Net charge-offs to average loans............................      0.16
End of period allowance for loan losses to end of period
  loans.....................................................      1.18
Non-performing loans to total loans.........................      0.40
Leverage ratio..............................................      7.16
Tier 1 capital to risk adjusted assets......................     10.73
Efficiency ratio(4).........................................     56.23
</TABLE>

- -------------------------
(1) Restated for all stock dividends.

(2) Assumes the conversion of Old National's subordinated debentures.
(3) Excludes unrealized gains (losses) on investment securities.
(4) Excludes charter consolidation expenses and security gains (losses). See "--
    One Bank."

ONE BANK

     On July 24, 1998, Old National announced its plan to merge its banking
subsidiaries into Old National Bank, its largest subsidiary, to improve
operational efficiencies while maintaining its emphasis on community banking.
These mergers are completed with the exception of one which will occur in early
2000. Additionally, Old National expects to maintain one Indiana state-chartered
bank subsidiary in order to continue to offer its customers a full range of
insurance products. Old National currently expects that by the first quarter of
2000, all of Old National's current banking offices will operate under a common
name and offer a broader range of products and services. Following the merger,
customers will have the opportunity to perform all of their banking transactions
at any of Old National's banking offices or ATM locations.

ACQUISITIONS

     On July 29, 1999, Old National agreed to acquire ANB Corporation, a
multi-bank holding company headquartered in Muncie, Indiana, with assets of
approximately $833.9 million as of September 30, 1999. Under the terms of the
acquisition agreement, each shareholder of ANB will receive 1.3125 shares of
common stock of Old National for each outstanding share of common stock of ANB
that they own. The transaction value is approximately $212.4 million based on
the market value of Old National's common stock on July 29, 1999. The closing of
this acquisition is expected to occur on March 10, 2000 and is subject to
shareholder and regulatory approvals and satisfaction of certain other
conditions contained in the acquisition agreement between Old National and ANB.

     On September 8, 1999, Old National agreed to acquire Heritage Financial
Services, Inc., a bank holding company headquartered in Clarksville, Tennessee,
with assets of approximately $234.0 million as of September 30, 1999. Under the
terms of the acquisition agreement, each shareholder of Heritage Financial
Services will receive 3.3075 shares of Old National's common stock for each
outstanding share of common stock of Heritage Financial Services that they own.
Based on the value of Old National's common stock as of September 8, 1999, the
transaction value is approximately $63.2 million. The closing of this
acquisition occurred on March 1, 2000.
                                      S-12
<PAGE>   13

     On December 20, 1999, Old National agreed to acquire Permanent Bancorp,
Inc., a unitary savings and loan holding company headquartered in Evansville,
Indiana, with assets of approximately $502.0 million as of September 30, 1999.
Under the terms of the acquisition agreement, the stockholders of Permanent
Bancorp will receive shares of common stock of Old National for their shares of
common stock of Permanent Bancorp. The transaction value is approximately $92.0
million, subject to adjustment based upon changes in the market price of Old
National's common stock. The closing of this acquisition is expected to occur
early next year and is subject to stockholder and regulatory approval and
satisfaction of certain other conditions contained in the acquisition agreement.
Old National intends for the branches of Permanent Bank, a subsidiary of
Permanent Bancorp, to become branches of Old National Bank.

     Upon completion of the acquisitions of ANB, Heritage Financial Services and
Permanent Bancorp, Old National's number of banking offices will increase to 153
and its number of ATMs will increase to 227 throughout Indiana, Illinois,
Kentucky, Ohio and Tennessee.

     On December 31, 1999, Old National, through an affiliate, acquired Sycamore
Agency, Inc., an Indiana corporation headquartered in Terre Haute, Indiana,
which operates a general insurance agency with a focus on commercial property
and casualty business. Sycamore Agency also provides a full line of personal and
group accident and health coverages to its clients. Sycamore Agency markets its
products primarily in Indiana and Illinois. Sycamore Agency sold policies with
annual premiums of $27.5 million in 1998. The acquisition of Sycamore Agency was
accomplished by the shareholders of Sycamore Agency exchanging all of their
shares of common stock of Sycamore Agency for shares of common stock of Old
National. The transaction value is approximately $10.8 million based on the
value of Old National's common stock on December 31, 1999.

                              ACCOUNTING TREATMENT

     ONB Capital Trust I will be treated as a subsidiary of Old National, and
the accounts of ONB Capital Trust I will be included in its consolidated
financial statements. The preferred securities will be presented as a separate
line item in Old National's balance sheet entitled "Guaranteed Preferred
Beneficial Interests in Company's Subordinated Debentures," and disclosures
concerning the preferred securities, the guarantee and the junior subordinated
debentures will be included in the notes to the financial statements.

                           DESCRIPTION OF SECURITIES

     This prospectus supplement discloses the specific terms and provisions of
the preferred securities and the junior subordinated debentures and supplements
the general description of the terms and provisions of these securities in the
accompanying prospectus. These summaries are not meant to be a complete
description of each security. However, this prospectus supplement and the
accompanying prospectus contain the material terms and conditions for each
security. For more information, please refer to the trust agreement, the
indenture and the guarantee. Forms of these documents are filed as exhibits to
the registration statement of which this prospectus supplement and the
accompanying prospectus are a part. All terms used in this prospectus supplement
have the meanings given to them in these documents.

                                      S-13
<PAGE>   14

                   CERTAIN TERMS OF THE PREFERRED SECURITIES

DISTRIBUTIONS

     The preferred securities represent undivided beneficial interests in the
assets of ONB Capital Trust I. Distributions on the preferred securities are
cumulative and will accumulate from the date they are first issued at the annual
rate of 9.500% of the $25 per preferred security liquidation amount.
Distributions will be payable quarterly in arrears on March 30, June 30,
September 30 and December 30 of each year, beginning June 30, 2000.
Distributions not paid when due will themselves accumulate additional
distributions, compounded quarterly, at the annual rate of 9.500% on the amount
of unpaid distributions, to the extent permitted by law. The term
"distributions" includes any of these distributions. The amount of distributions
payable for any period will be computed on the basis of a 360-day year of twelve
30-day months.

     So long as no event of default has occurred and is continuing under the
junior subordinated debentures, Old National may, at any time and from time to
time, defer interest payments on the junior subordinated debentures for up to 20
consecutive quarters. A deferral of interest payments cannot extend, however,
beyond the maturity date of the junior subordinated debentures. Before a
deferral period ends, Old National may extend it if that deferral period does
not exceed 20 consecutive quarters or extend beyond the stated maturity of the
junior subordinated debentures. When a deferral period ends and Old National has
paid all accrued and unpaid interest on the junior subordinated debentures, Old
National may begin a new deferral period, subject to the terms described above.
There is no limit on the number of deferral periods that Old National may begin.

     If Old National defers interest payments on the junior subordinated
debentures, ONB Capital Trust I will similarly defer quarterly distributions on
the preferred securities during the deferral period. During a deferral period
the amount of distributions due to you will continue to accumulate at the rate
stated above, and these deferred distributions will themselves accrue interest,
to the extent permitted by law.

     Old National has no current intention to exercise its right to defer
interest payments on the junior subordinated debentures issued to ONB Capital
Trust I. If Old National defers interest payments on the junior subordinated
debentures, it would be subject to certain restrictions relating to the payment
of dividends on or purchases of its capital stock and payments on its debt
securities ranking equal with or junior to the junior subordinated debentures.
See "Description of Debt Securities -- Certain Provisions Relating to Junior
Subordinated Debentures Issued to the ONB Trusts -- Option to Defer Interest
Payment Date" in the accompanying prospectus.

     See the accompanying prospectus for additional terms of the preferred
securities, including provisions relating to the deferral of distributions, the
payment of distributions and the subordination of the common securities.

     If distributions are payable on a date that is not a business day, payment
will be made on the next business day, without any interest or other payment in
respect of the delay in payment. However, if the next business day is in the
next calendar year, payment of distributions will be made on the preceding
business day. A "business day" means each Monday, Tuesday, Wednesday, Thursday
or Friday which is not a day on which banking institutions in New York City are
authorized or obligated by law, regulation or executive order to close, or a day
on which the Federal Reserve Bank of New York is not open.

REDEMPTION

     General. ONB Capital Trust I must redeem all of the outstanding preferred
securities when the junior subordinated debentures are paid at maturity on March
15, 2030. Old National can redeem the junior subordinated debentures prior to
maturity (a) in whole or in part at any time after March 15, 2005, or (b) in
whole but not in part if a Special Event as described below has occurred and is
continuing. Prior to any such redemption, Old National will obtain any required
regulatory approval. When Old National redeems the junior subordinated
debentures, the property trustee will use the proceeds to redeem a like amount
of the preferred securities and common securities. The property trustee will
give you at least

                                      S-14
<PAGE>   15

30 days, but not more than 60 days, notice before the redemption date. The
preferred securities and (unless there is a default under the junior
subordinated debentures) common securities will be redeemed at a price equal to
the liquidation amount of $25 per security plus accrued and unpaid distributions
to the date of redemption.

     If less than all of the preferred securities and common securities are
redeemed, then the aggregate liquidation amount of preferred securities and
common securities to be redeemed will be allocated 3% to the common securities
holders, subject to the exceptions as described in "Description of Capital
Securities -- Subordination of Common Securities" in the accompanying prospectus
and 97% to the holders of preferred securities. The preferred securities and
(unless there is a default under the junior subordinated debentures) common
securities to be redeemed will be selected by the property trustee by a method
determined to be fair and appropriate by it subject to the subordination
provisions of the common securities.

     See the accompanying prospectus for other redemption provisions and for
redemption procedures.

     Special Event Redemption. If a Tax Event, an Investment Company Event or a
Regulatory Capital Event, each as defined in the accompanying prospectus (each,
a "Special Event"), has occurred and is continuing, Old National may redeem the
junior subordinated debentures, in whole but not in part. This will cause a
mandatory redemption of the preferred securities and the common securities, in
whole but not in part, within 90 days following the occurrence of the Special
Event, at the $25 per security liquidation amount plus unpaid distributions to
the date of redemption. See "Description of Debt Securities -- Certain
Provisions Relating to Junior Subordinated Debentures Issued to the ONB
Trusts -- Redemption" in the accompanying prospectus.

     However, in the case of an occurrence of a Special Event, if Old National
can eliminate, within the 90 day period, the Special Event by taking some
action, such as filing a form or making an election, or pursuing some other
similar reasonable measure which has no adverse effect on Old National, ONB
Capital Trust I or the holders of the preferred securities or the common
securities, Old National will pursue that action instead of redemption. Old
National will have no right to redeem the junior subordinated debentures while
ONB Capital Trust I or the property trustee is pursuing any similar action based
on its obligations under the trust agreement.

     If a Tax Event is continuing and Old National does not redeem the junior
subordinated debentures or liquidate ONB Capital Trust I, Old National will pay
additional amounts, if any, to the holders of the junior subordinated debentures
so that, notwithstanding any additional taxes, duties or charges imposed on ONB
Capital Trust I because of the Tax Event, ONB Capital Trust I will have
sufficient funds to pay the full amount of distributions due on the outstanding
preferred securities. For a discussion of other additional amounts that Old
National will pay to ONB Capital Trust I, see "Description of Capital
Securities -- Additional Amounts" in the accompanying prospectus.

              CERTAIN TERMS OF THE JUNIOR SUBORDINATED DEBENTURES

     ONB Capital Trust I will use the proceeds of the issuance of the preferred
securities and the common securities to purchase junior subordinated debentures
issued by Old National. Old National will issue junior subordinated debentures
to ONB Capital Trust I in an aggregate principal amount of $51,546,392. The
junior subordinated debentures will be issued as a series pursuant to a
securities resolution dated as of March 9, 2000, under the indenture. The junior
subordinated debentures will be unsecured and will rank subordinate and junior
in right of payment to all of the Senior Debt.

INTEREST RATE AND MATURITY

     The junior subordinated debentures will mature on March 15, 2030, and will
bear interest at the annual rate of 9.500% of the principal amount thereof,
payable quarterly in arrears on March 30, June 30, September 30 and December 30
of each year, beginning June 30, 2000. Interest payments not paid when due will
themselves accrue additional interest compounded quarterly at the annual rate of
9.500% on the amount of unpaid interest to the extent permitted by law. The term
"interest payments" includes this additional interest. The amount of interest
payable for any period will be computed based on a 360-day
                                      S-15
<PAGE>   16

year of twelve 30-day months. The interest payment provisions for the junior
subordinated debentures correspond to the distribution provisions of the
preferred securities.

     So long as no event of default has occurred and is continuing under the
junior subordinated debentures, Old National may, at any time and from time to
time, defer interest payments on the junior subordinated debentures for up to 20
consecutive quarters. A deferral of interest payments cannot extend, however,
beyond the maturity date of the junior subordinated debentures. Before a
deferral period ends, Old National may extend it if that deferral period does
not exceed 20 consecutive quarters or extend beyond the stated maturity of the
junior subordinated debentures. When a deferral period ends and Old National has
paid all accrued and unpaid interest on the junior subordinated debentures, Old
National may begin a new deferral period, subject to the terms described above.
There is no limit on the number of deferral periods that Old National may begin.

     Old National has no current intention to exercise its right to defer
interest payments on the junior subordinated debentures issued to ONB Capital
Trust I. If Old National defers interest payments on the junior subordinated
debentures, it would be subject to certain restrictions relating to the payment
of dividends on or purchases of its capital stock and payments on its debt
securities ranking equally with or junior to the junior subordinated debentures.
See "Description of Debt Securities -- Certain Provisions Relating to Junior
Subordinated Debentures Issued to the ONB Trusts -- Option to Defer Interest
Payment Date" in the accompanying prospectus.

     See the accompanying prospectus for additional terms of the junior
subordinated debentures.

REDEMPTION

     Old National has the option to redeem the junior subordinated debentures
prior to maturity at a redemption price equal to 100% of the principal amount
plus accrued and unpaid interest to the redemption date (a) in whole or in part
at any time on or after March 15, 2005, or (b) in whole but not in part if a
Special Event has occurred and is continuing.

DISTRIBUTION OF JUNIOR SUBORDINATED DEBENTURES

     If the property trustee distributes the junior subordinated debentures to
the holders of the preferred securities and the common securities upon the
termination and liquidation of ONB Capital Trust I, the junior subordinated
debentures will be issued in denominations of $25 and integral multiples
thereof. Old National anticipates that the junior subordinated debentures would
be distributed in the form of one or more global securities and DTC, or any
successor depositary for the preferred securities, would act as depositary for
the junior subordinated debentures. The depositary arrangements for the junior
subordinated debentures would be substantially similar to those in effect for
the preferred securities.

     For a description of DTC and the terms of the depository arrangements
relating to payments, transfers, voting rights, redemption and other notices and
other matters, see "Book-Entry Issuance" in the accompanying prospectus.

                     UNITED STATES FEDERAL INCOME TAXATION

GENERAL

     The following summary of U.S. federal income tax consequences material to
the purchase, ownership and disposition of the preferred securities is based on
the views of Krieg DeVault Alexander & Capehart, LLP, tax counsel to Old
National and ONB Capital Trust I. It does not purport to be a comprehensive
description of all of the tax consequences that may be relevant to a decision to
purchase preferred securities by any particular investor, including tax
consequences that arise from rules of general application to all taxpayers or to
certain classes of taxpayers or that are generally assumed to be known by
investors. This summary is based on (1) the Internal Revenue Code of 1986, as
amended (the "Code"), (2) income tax regulations issued under the Code and (3)
associated administrative and judicial interpretations, all as they currently
exist as of the date of this prospectus supplement. These income tax laws and
regulations, however, may change at any time, and any change could be
retroactive to the issuance date of the preferred securities.

                                      S-16
<PAGE>   17

     These income tax laws and regulations are also subject to various
interpretations, and the Internal Revenue Service (the "IRS") or the courts
could later disagree with what Old National explains in this summary. The IRS
has not formally ruled (and Old National does not intend to seek a ruling) on
the tax consequences material to the purchase, ownership and disposition of the
preferred securities. Accordingly, the IRS could challenge the opinions
expressed in this prospectus supplement concerning such consequences, and a
court could agree with the IRS.

     Except where this summary states otherwise, the summary deals only with
preferred securities held as a capital asset (as defined in section 1221 of the
Code) by a holder who (a) purchases the preferred securities at their original
offering price when ONB Capital Trust I originally issues them (an "Initial
Holder") and (b) is a U.S. Holder (as defined below).

     This summary does not address, except as stated below, any of the tax
consequences to holders that are not U.S. Holders or to holders that may be
subject to special tax treatment such as banks, thrift institutions, real estate
investment trusts, regulated investment companies, insurance companies, brokers
and dealers in securities or currencies, tax-exempt investors or persons that
will hold the preferred securities as a position in a "straddle," as part of a
"hedge," or as part of a "conversion transaction" or other integrated
investment, or persons having a functional currency other than the U.S. dollar.
Further, this summary does not address:

     - the United States federal income tax consequences to shareholders in, or
       partners, members or beneficiaries of, a holder of the preferred
       securities;

     - the United States federal alternative minimum tax consequences material
       to the purchase, ownership or disposition of the preferred securities; or

     - any state, local or foreign tax consequences material to the purchase,
       ownership or disposition of the preferred securities.

     A "U.S. Holder" is a preferred securities holder who or which is:

     - a United States citizen or resident individual (or someone treated as a
       citizen or resident individual for United States federal income tax
       purposes);

     - a corporation (including an entity treated as a corporation for United
       States federal income tax purposes) created or organized (or treated as
       created or organized) in or under the laws of the United States or any
       state or other political subdivision thereof;

     - any other person that is subject to United States federal income taxation
       on a net income basis in respect of the investment in the preferred
       securities.

     A "Non-U.S. Holder" is a preferred securities holder that is a nonresident
alien or a foreign corporation.

CHARACTERIZATION OF THE JUNIOR SUBORDINATED DEBENTURES AND ONB CAPITAL TRUST I

     In connection with the issuance of the junior subordinated debentures,
Krieg DeVault Alexander & Capehart, LLP, tax counsel to Old National and ONB
Capital Trust I, will render its opinion that, under then current law, and
assuming full compliance with the terms of the trust agreement, the underwriting
agreement governing the sale of the preferred securities by Old National to the
underwriters and the indenture (and other relevant documents), and based on
certain facts and assumptions contained in such opinion, the junior subordinated
debentures will be classified for United States federal income tax purposes as
indebtedness of Old National. By acceptance of a preferred security, you agree
to treat the junior subordinated debentures as indebtedness and the preferred
securities as an undivided beneficial ownership interest in the junior
subordinated debentures.

     In connection with the issuance of the preferred securities, Krieg DeVault
Alexander & Capehart, LLP will render its opinion that, under current law and
assuming full compliance with the terms of the trust agreement, the underwriting
agreement governing the sale of the preferred securities by Old National
                                      S-17
<PAGE>   18

to the underwriters and the indenture (and other relevant documents), and based
on certain facts and assumptions contained in such opinion, ONB Capital Trust I
will be characterized for United States federal income tax purposes as a grantor
trust and not as an association that is taxable as a corporation. Accordingly,
for United States federal income tax purposes, you will be considered the owner
of an undivided beneficial ownership interest in the junior subordinated
debentures, and you will be required to include in your gross income any
interest (or original issue discount accrued) with respect to your allocable
share of those junior subordinated debentures. See "-- Interest Income and
Original Issue Discount," below.

INTEREST INCOME AND ORIGINAL ISSUE DISCOUNT

     Under applicable income tax regulations, if there is only a remote
likelihood that a company will not make its interest payments on time, then the
debt will be considered to be issued without original issue discount ("OID").
Old National believes that the likelihood that it will exercise its option to
defer interest payments is remote, since this would prevent Old National from
declaring dividends on any of its capital stock or making payments on its debt
securities that rank equal with or junior to the junior subordinated debentures
until it paid in full all of the missed interest payments. Accordingly, Old
National will take the position that the junior subordinated debentures will not
be issued with OID. Under this approach, the interest payments on the junior
subordinated debentures (which are used to make distributions on the preferred
securities) generally will be taxable to you as ordinary income when they are
paid or accrued depending on your method of United States federal income tax
accounting.

     If, however, the possibility that Old National would exercise its option to
defer payments of interest were determined not to be "remote," or if Old
National were to exercise its option to defer payments of interest, the junior
subordinated debentures would be treated as issued with OID at the time of
issuance, or as re-issued with OID at the time of such exercise, as the case may
be, and all stated interest on the junior subordinated debentures would
thereafter be treated as OID as long as the junior subordinated debentures
remained outstanding. In that case, all of your taxable interest income with
respect to the junior subordinated debentures would have to be accounted for as
OID using a constant yield method regardless of your method of United States
federal income tax accounting, and actual distributions of stated interest would
not be reported as taxable income. Consequently, you would be required to
include OID in your gross income even though Old National would not make any
actual cash payments during the deferral period.

     The IRS has not issued any rulings or interpretations that define the
meaning of the term "remote" as used in the applicable income tax regulations.
The IRS could take a position that differs from what is stated in this
prospectus supplement.

CORPORATE U.S. HOLDERS

     Because the income from the preferred securities will not be considered to
be dividends for United States federal income tax purposes, corporate U.S.
Holders of the preferred securities will not be entitled to a dividends-received
deduction for any income from the preferred securities.

MARKET DISCOUNT AND ACQUISITION PREMIUM

     Holders of the preferred securities other than Initial Holders may be
considered to have acquired their undivided interests in the junior subordinated
debentures with "market discount" or "acquisition premium" (as each phrase is
defined for United States federal income tax purposes). Such holders are urged
to consult with their own tax advisors concerning the tax consequences of
purchasing, owning and selling the preferred securities.

SALES OF PREFERRED SECURITIES

     If you sell your preferred securities, you will recognize a gain or loss
equal to the difference between the amount realized from the sale of the
preferred securities (generally, your selling price minus any
                                      S-18
<PAGE>   19

portion attributable to accrued but unpaid interest not otherwise includible as
OID) and your adjusted tax basis in the preferred securities. If Old National
does not defer interest on the junior subordinated debentures and the debentures
are not treated as issued with OID, your adjusted tax basis in the preferred
securities generally will equal the initial purchase price that you paid for the
preferred securities. If, however, Old National elects to defer interest
payments on the junior subordinated debentures, or if the debentures were
treated as issued with OID, your adjusted tax basis in the preferred securities
generally will equal (1) the initial purchase price that you paid for the
preferred securities plus (2) any OID accrued to the date of disposition, less
(3) all distributions since and including the date of the first deferral period
or the date or issuance, as the case may be.

     Except to the extent of any accrued market discount, a gain or loss on the
sale of preferred securities generally will be a capital gain or loss if the
preferred securities are held as capital assets. With certain exceptions, the
maximum regular United States federal income tax rate on capital gains for
individual taxpayers is currently 20% for sales and exchanges of capital assets
held for more than one year. Subject to certain limited exceptions, capital
losses cannot be applied to offset ordinary income for United States federal
income tax purposes.

     If you use the accrual method of accounting for tax purposes (or the cash
method, if the junior subordinated debentures are deemed to have been issued
with OID) and you dispose of the preferred securities between record dates for
payments of distributions thereon, you will be required to include in gross
income for United States federal income tax purposes accrued but unpaid interest
on the junior subordinated debentures through the date of disposition (i.e.,
interest or, possibly, OID), and to add such amount to your adjusted tax basis
in accordance with your pro rata share of the underlying junior subordinated
debentures deemed disposed of. To the extent the selling price is less than your
adjusted tax basis (which will include all accrued but unpaid interest), you
will recognize a capital loss.

RECEIPT OF JUNIOR SUBORDINATED DEBENTURES OR CASH UPON LIQUIDATION OF ONB
CAPITAL TRUST I

     Under certain circumstances, as described in the accompanying prospectus
under "Description of Capital Securities -- Liquidation Distribution upon
Termination," the property trustee may distribute the junior subordinated
debentures to you in exchange for your preferred securities, after satisfaction
of any liabilities to creditors as may be provided by applicable law. This will
result in the liquidation and termination of ONB Capital Trust I. Except as set
forth below, such a distribution will not be a taxable event for United States
federal income tax purposes, and you will have an aggregate adjusted tax basis
in the junior subordinated debentures you receive equal to your aggregate
adjusted tax basis in your preferred securities. For a description of adjusted
tax basis, see the discussion above in "-- Sales of Preferred Securities."

     Further, the holding period of the junior subordinated debentures you
receive will be the same as the period for which you held your preferred
securities. If, however, the distribution were caused by a Tax Event because ONB
Capital Trust I was taxable as a corporation, the distribution would be a
taxable event for United States federal income tax purposes. In that case, you
could recognize a gain or loss, your adjusted tax basis in the junior
subordinated debentures could differ from your adjusted tax basis in the
preferred securities, and your holding period for the junior subordinated
debentures would not include the period during which you held the preferred
securities.

     The junior subordinated debentures may be redeemed for cash under certain
circumstances, and the proceeds would be used by the property trustee to redeem
a like amount of preferred securities. Such a redemption of preferred securities
would be a taxable event for United States federal income tax purposes, and you
would recognize gain or loss as if you had sold the preferred securities for
cash. See "-- Sales of Preferred Securities," above.

                                      S-19
<PAGE>   20

NON-U.S. HOLDERS

     Payments to a Non-U.S. Holder will generally not be subject to United
States federal withholding tax, provided the holder:

     - does not own (directly or indirectly, actually or constructively) 10% or
       more of the total combined voting power of all classes of stock of Old
       National entitled to vote; and

     - is not a controlled foreign corporation that is related to Old National
       actually or constructively through stock ownership.

     To qualify for this exemption from withholding, the last United States
payer in the chain of payment prior to payment to a Non-U.S. Holder (the
"Withholding Agent") must have received a statement that:

     - is signed by the holder of the preferred securities under penalties of
       perjury;

     - certifies that such holder is not a U.S. Holder; and

     - provides the name and address of the holder.

     The statement may be made on an appropriate IRS Form W-8, W-8BEN or a
substantially similar form. If the preferred securities are held through a
securities clearing organization or certain other financial institutions, the
organization or institution may provide a signed statement to the Withholding
Agent along with a copy of the form provided by the holder.

     A Non-U.S. Holder will generally not be subject to United States federal
withholding or income tax on any gain realized upon the sale or other
disposition of the preferred securities. However, if a Non-U.S. Holder holds the
preferred securities in connection with a trade or business conducted in the
United States, or is present in the United States in certain circumstances, the
holder may be subject to income tax on income and gains recognized. Non-U.S.
Holders who may be described in the prior sentence should refer to the
discussion applicable to U.S. Holders, above, and should consult their own tax
advisors.

BACKUP WITHHOLDING TAX AND INFORMATION REPORTING

     The amount of interest income paid and OID accrued on the preferred
securities held of record by U.S. Holders (other than corporations and other
exempt U.S. Holders) will be reported to the IRS. "Backup" withholding at a rate
of 31% will apply to payments of interest to nonexempt U.S. Holders unless the
U.S. Holder furnishes its taxpayer identification number in the manner
prescribed in applicable tax regulations, certifies that such number is correct,
certifies as to no loss of exemption from backup withholding and meets certain
other conditions.

     Payment of the proceeds from the disposition of preferred securities to or
through the United States office of a broker is subject to information reporting
and backup withholding unless the holder or beneficial owner establishes an
exemption from information reporting and backup withholding.

     Any amounts withheld from a U.S. Holder under the backup withholding rules
will be allowed as a refund or a credit against such U.S. Holder's United States
federal income tax liability, provided the required information is furnished to
the IRS.

     It is anticipated that income on the preferred securities will be reported
to holders on Form 1099-INT or, if Old National exercises its option to defer
any payment of interest, Form 1099-OID, and mailed to holders of the preferred
securities by January 31 following each calendar year.

The tax information above is intended only as a summary of material United
States federal tax consequences of an investment in ONB Capital Trust I. Old
National urges you to consult with your own tax advisors as to the United States
federal, state and local, and foreign and other tax consequences material to the
purchase, ownership or disposition of preferred securities. The statements of
United States tax laws described above are based on the laws in force as of the
date of this prospectus supplement and are subject to any changes in United
States law occurring after that date.
                                      S-20
<PAGE>   21

                              ERISA CONSIDERATIONS

     Each fiduciary of a pension, profit-sharing or other employee benefit plan
subject to the Employee Retirement Income Security Act of 1974, as amended
("ERISA"), (a "Plan") should consider the fiduciary standards of ERISA in the
context of the Plan's particular circumstances before authorizing an investment
in the capital securities. Accordingly, among other factors, the fiduciary
should consider whether the investment would satisfy the prudence and
diversification requirements of ERISA and would be consistent with the documents
and instruments governing the Plan.

     Section 406 of ERISA and section 4975 of the Code prohibit Plans, as well
as individual retirement accounts, Keogh plans and other plans subject to
section 4975 of the Code (also "Plans"), from engaging in certain transactions
involving "plan assets" with persons that are "parties in interest" under ERISA
or "disqualified persons" under the Code with respect to the Plan. A violation
of these "prohibited transaction" rules may result in an excise tax or other
liabilities under ERISA and/or section 4975 of the Code being imposed on such
persons, unless exemptive relief is available under an applicable statutory or
administrative exemption. Employee benefit plans that are governmental plans (as
defined in section 3(32) of ERISA), certain church plans (as defined in 3(33) of
ERISA) and foreign plans (as described in section 4(b)(4) of ERISA) are not
subject to the requirements of ERISA or section 4975 of the Code, but may be
subject to similar provisions of other applicable local, state, federal or
foreign laws.

     Under a regulation issued by the U.S. Department of Labor, the assets of
ONB Capital Trust I would be deemed to be "plan assets" of a Plan for purposes
of ERISA and section 4975 of the Code if "plan assets" of the Plan were used to
acquire an equity interest in ONB Capital Trust I and no exception were
applicable under the regulation. An "equity interest" is defined under the
regulation as any interest in an entity other than an instrument which is
treated as indebtedness under applicable local law and which has no substantial
equity features; the definition specifically includes a beneficial interest in a
trust.

     Certain transactions involving ONB Capital Trust I could be deemed to
constitute direct or indirect prohibited transactions under ERISA and section
4975 of the Code with respect to a Plan if the preferred securities of ONB
Capital Trust I were acquired with "plan assets" of the Plan. For example, if
Old National is a "party in interest" or "disqualified person" with respect to
an investing Plan (either directly or by reason of its ownership of its
subsidiaries), an indirect extension of credit prohibited by section
406(a)(1)(B) of ERISA and section 4975(c)(1)(B) of the Code between Old National
and the investing Plan may be deemed to occur, unless exemptive relief were
available under an applicable administrative exemption (see below).

     The U.S. Department of Labor has issued five prohibited transaction class
exemptions ("PTCEs") that may provide exemptive relief for direct or indirect
prohibited transactions resulting from the purchase or holding of the preferred
securities. Those class exemptions are:

     - PTCE 96-23 -- for certain transactions determined by in-house asset
       managers,

     - PTCE 95-60 -- for certain transactions involving insurance company
       general accounts,

     - PTCE 91-38 -- for certain transactions involving bank collective
       investment funds,

     - PTCE 90-1 -- for certain transactions involving insurance company
       separate accounts, or

     - PTCE 84-14 -- for certain transactions determined by independent
       qualified professional asset managers.

     Because of the possibility that direct or indirect prohibited transactions
could occur as a result of the purchase or holding of the preferred securities
by a Plan, the preferred securities may be not purchased or held by any Plan,
any entity whose underlying assets include "plan assets" by reason of any Plan's
investment in the entity (a "Plan Asset Entity") or any person investing "plan
assets" of any Plan, unless such purchase or holding is eligible for the
exemptive relief available under PTCE 96-23, 95-60, 91-38, 90-1 or 84-14. Any
purchaser or holder of the preferred securities or any interest therein will be
deemed to have represented by its purchase and holding thereof that either

                                      S-21
<PAGE>   22

     - it is not a Plan or a Plan Asset Entity and is not purchasing such
       preferred securities or interest therein on behalf of or with "plan
       assets" of any Plan; or

     - its purchase, holding and disposition of the preferred securities or
       interest therein is eligible for the exemptive relief available under
       PTCE 96-23, 95-60, 91-38, 90-1 or 84-14.

     The "plan assets" regulation discussed above contains an exception for
investments by Plans in certain "publicly-offered securities." In order to
qualify for this exception, the securities in question must be: (i) "freely
transferable;" (ii) part of a class of securities that is owned by 100 or more
investors independent of the issuer and of one another; and (iii) either (a)
part of a class of securities registered under Section 12(b) or 12(g) of the
Securities Exchange Act of 1934, or (b) sold as part of a public offering
pursuant to an effective registration statement under the Securities Act of 1933
and registered under the Securities Exchange Act of 1934 within 120 days (or
such later time as may be allowed by the SEC) after the end of the issuer's
fiscal year during which the offering occurred.

     It is currently anticipated that the preferred securities will be "freely
transferable" for purposes of this exception and will be owned by at least 100
investors independent of the issuer and of one another. Finally, no preferred
securities will be sold except pursuant to an effective registration statement
under the Securities Act of 1933, and it is intended that the required filings
under the Securities Exchange Act of 1934 will be made for purposes of this
exception. Therefore, ONB Capital Trust I should qualify for the exception, so
that the assets of ONB Capital Trust I should not be "plan assets" of any Plan
investing in the preferred securities, and ONB Capital Trust I underlying assets
should not be treated as "plan assets" of Plan investors for purposes of
determining whether any prohibited transaction has occurred.

     Due to the complexity of these rules and the penalties imposed upon persons
involved in non-exempt prohibited transactions, it is important that any person
considering the purchase of preferred securities on behalf of or with "plan
assets" of any Plan consult with its counsel regarding the consequences under
ERISA and the Code of the acquisition and ownership of capital securities and
the availability of exemptive relief under PTCE 96-23, 95-60, 91-38, 90-1 and
84-14. In John Hancock Mutual Life Insurance Co. v. Harris Trust and Savings
Bank, 114 S. Ct. 517 (1993), the Supreme Court ruled that assets held in an
insurance company's general account may be deemed to be "plan assets" for ERISA
purposes under certain circumstances. The issues raised in Harris Trust have
also been the subject of legislative action, and have been addressed in proposed
regulations issued by the U.S. Department of Labor in December 1997.

                                      S-22
<PAGE>   23

                                  UNDERWRITING

     Subject to the terms and conditions of the underwriting agreement dated
March 9, 2000, each underwriter named below has severally agreed to purchase,
and ONB Capital Trust I has agreed to sell to such underwriter, the number of
preferred securities set forth opposite the name of such underwriter.

<TABLE>
<CAPTION>
                                                           NUMBER OF
NAME                                                  PREFERRED SECURITIES
- ----                                                  --------------------
<S>                                                   <C>
Salomon Smith Barney Inc. .........................          405,000
Merrill Lynch, Pierce, Fenner & Smith
  Incorporated.....................................          405,000
PaineWebber Incorporated...........................          405,000
Prudential Securities Incorporated.................          405,000
Stifel, Nicolaus & Company, Incorporated...........           80,000
ABN AMRO Incorporated..............................           15,000
A.G. Edwards & Sons, Inc...........................           15,000
Dain Rauscher Incorporated.........................           15,000
Deutsche Banc Alex. Brown Incorporated.............           15,000
First Union Capital Markets, Inc. .................           15,000
Fleet Securities, Inc. ............................           15,000
Howe Barnes Investments Inc........................           15,000
J.J.B. Hilliard, W.L. Lyons, Inc. .................           15,000
Janney Montgomery Scott Inc. ......................           15,000
J.C. Bradford & Co.................................           15,000
Keefe Bruyette & Woods.............................           15,000
Legg Mason Wood Walker, Incorporated...............           15,000
McDonald & Company Securities, Inc. ...............           15,000
NatCity Investments, Inc. .........................           15,000
Olde Discount Corporation..........................           15,000
Raymond James & Associates, Inc. ..................           15,000
Robert W. Baird & Co. Incorporated.................           15,000
The Robinson-Humphrey Company, LLC.................           15,000
Sandler O'Neill & Partners, L.P....................           15,000
U.S. Bancorp Piper Jaffray Inc. ...................           15,000
                                                           ---------
          Total....................................        2,000,000
                                                           =========
</TABLE>

     The underwriting agreement provides that the obligations of the several
underwriters to purchase the preferred securities included in this offering are
subject to approval of certain legal matters by counsel and to certain other
conditions. The underwriters are obligated to purchase all of the preferred
securities if they purchase any of the preferred securities.

     The underwriters, for whom Salomon Smith Barney Inc. is acting as
representative, propose to offer some of the preferred securities directly to
the public at the initial public offering price set forth on the cover page of
this prospectus supplement, and some of the preferred securities to certain
dealers at the initial public offering price less a concession of $0.50 per
preferred security. The underwriters may allow, and such dealers may reallow, a
concession not in excess of $0.35 per preferred security to certain brokers and
dealers. After the initial offering of the preferred securities to the public,
the public offering price and other selling terms may be changed by the
representative.

     In view of the fact that the proceeds of the sale of the preferred
securities will ultimately be used to purchase the junior subordinated
debentures, the underwriting agreement provides that Old National will pay as
compensation to the underwriters $0.7875 per preferred security for the accounts
of the several underwriters ($1,575,000 in the aggregate).

                                      S-23
<PAGE>   24

     In connection with the offering, Salomon Smith Barney Inc., on behalf of
the underwriters, may purchase and sell preferred securities in the open market.
These transactions may include over-allotment, syndicate covering transactions
and stabilizing transactions. Over-allotment involves syndicate sales of
preferred securities in excess of the principal amount of preferred securities
to be purchased by the underwriters in the offering, which creates a syndicate
short position. Syndicate covering transactions involve purchases of the
preferred securities in the open market after the distribution has been
completed in order to cover syndicate short positions. Stabilizing transactions
consist of certain bids or purchases of preferred securities made for the
purpose of preventing or retarding a decline in the market price of the
preferred securities while the offering is in progress.

     The underwriters also may impose a penalty bid. Penalty bids permit the
underwriters to reclaim a selling concession from a syndicate member when
Salomon Smith Barney Inc., in covering syndicate short positions or making
stabilizing purchases, repurchases preferred securities originally sold by that
syndicate member.

     Any of these activities may cause the price of the preferred securities to
be higher than the price that otherwise would exist in the open market in the
absence of such transactions. These transactions may be effected in the
over-the-counter market or otherwise and, if commenced, may be discontinued at
any time.

     The expenses associated with the offer and sale of the preferred securities
are estimated to be $294,100.

     Certain of the underwriters and their affiliates have in the past provided,
and may in the future provide, investment banking services to Old National and
its affiliates in the ordinary course of business.

     Old National and ONB Capital Trust I have agreed to indemnify the several
underwriters against certain liabilities, including liabilities under the
Securities Act of 1933, as amended, or contribute to payments the underwriters
may be required to make in respect of any of those liabilities.

     Application will be made to list the preferred securities on the New York
Stock Exchange. If approved, trading of the preferred securities on the New York
Stock Exchange is expected to commence within a 30-day period after the initial
delivery of the preferred securities. Prior to this offering, there has been no
public market for the preferred securities. In order to meet one of the
requirements for listing the preferred securities on the New York Stock
Exchange, the underwriters will undertake to sell lots of 100 or more preferred
securities to a minimum of 400 beneficial holders.

     Old National and ONB Capital Trust I have agreed, during the period of 15
days from the date of the underwriting agreement, not to sell, offer to sell,
grant any option for the sale of, or otherwise dispose of any preferred
securities, any security convertible into or exchangeable into or exercisable
for preferred securities or the junior subordinated debentures or any debt
securities substantially similar to the junior subordinated debentures or equity
securities substantially similar to the preferred securities (except for the
junior subordinated debentures and the preferred securities issued pursuant to
the underwriting agreement), without the prior written consent of the
representatives.

                                 LEGAL MATTERS

     Matters of Delaware law relating to the validity of the preferred
securities will be passed upon on behalf of Old National and ONB Capital Trust I
by Richards, Layton & Finger, P.A., Wilmington, Delaware, special Delaware
counsel to Old National and ONB Capital Trust I. The validity of the junior
subordinated debentures and the guarantee and certain matters relating to United
States federal income tax considerations will be passed upon on behalf of Old
National and ONB Capital Trust I by Krieg DeVault Alexander & Capehart, LLP.
Certain legal matters will be passed upon for the underwriters by Cleary,
Gottlieb, Steen & Hamilton, Washington, D.C.

                                      S-24
<PAGE>   25

PROSPECTUS

                                  $200,000,000

                              OLD NATIONAL BANCORP
                                DEBT SECURITIES
                           -------------------------

                              ONB CAPITAL TRUST I
                              ONB CAPITAL TRUST II
                             ONB CAPITAL TRUST III
                              ONB CAPITAL TRUST IV
                               CAPITAL SECURITIES
         FULLY AND UNCONDITIONALLY GUARANTEED, AS DESCRIBED HEREIN, BY
                              OLD NATIONAL BANCORP
THE ONB TRUSTS:

- - will issue and sell capital securities (representing undivided beneficial
  interests in a trust) to the public;

- - will issue and sell common securities to Old National; and

- - will use the proceeds from these sales to buy a series of junior subordinated
  debentures from Old National with terms that correspond to the capital
  securities.

OLD NATIONAL:

- - will pay principal and interest on the junior subordinated debentures, subject
  to payment on its more senior debt;

- - may choose to terminate a trust and distribute the junior subordinated
  debentures pro rata to the holders of capital securities and common
  securities;

- - will fully and unconditionally guarantee the capital securities on a junior
  subordinated level based on:

  - its obligations to make payments on the corresponding junior subordinated
    debentures;

  - its obligations under the capital securities guarantee (its payment
    obligations are subordinated to payment on all of its Senior Debt); and

  - its obligations under the trust agreement; and

- - may also issue and sell other debt securities to the public.

Old National urges you to read this prospectus and the prospectus supplement
carefully before you make your investment decision.

Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or determined if this
prospectus is truthful or complete. Any representation to the contrary is a
criminal offense.

The date of this prospectus is February 29, 2000.
<PAGE>   26

                             ABOUT THIS PROSPECTUS

     In this prospectus, "Old National" refers to Old National Bancorp, a
"trust" or an "ONB Trust" refers to either ONB Capital Trust I, ONB Capital
Trust II, ONB Capital Trust III or ONB Capital Trust IV, which are the Delaware
statutory business trusts that Old National has formed to issue the capital
securities, and "we" or "us" refers to both Old National and the ONB Trusts.

     This prospectus is part of a registration statement that we file with the
SEC utilizing a "shelf" registration process. Under this shelf process, Old
National or the ONB Trusts may issue and sell to the public any combination of
the securities described in this prospectus in one or more offerings up to a
total dollar amount of $200,000,000.

     This prospectus provides you with only a general description of the
securities we may issue and sell. Each time Old National or an ONB Trust issues
and sells securities, we will provide a prospectus supplement that will contain
specific information about the particular securities and terms of that offering.
In the prospectus supplement, we will describe the interest rate, payment dates,
maturity and other terms of any debt securities that Old National issues and
sells, and the rights to periodic cash distributions, payments on liquidation
and other terms of a trust's capital securities. The prospectus supplement will
also describe the proceeds and uses of proceeds from the securities, together
with the names and compensation of the underwriters through whom the securities
are being issued and sold, and other important considerations for investors. It
may also add to, update or change information contained in this prospectus.

     Unless we say otherwise in the prospectus supplement, Old National may
redeem its debt securities for cash, or cause the trusts to liquidate and give
investors Old National's debt securities in place of the ONB Trusts' capital
securities.

               FORWARD-LOOKING STATEMENTS AND CAUTIONARY FACTORS

     We have included or may include statements in this prospectus and any
prospectus supplement (including documents incorporated by reference described
under the heading "Where You Can Find More Information" below) that constitute
forward-looking statements within the meaning of the Private Securities
Litigation Reform Act of 1995. You will be able to recognize a forward-looking
statement because it contains the words "anticipate," "believe," "estimate,"
"expect," "project," "objective" or a similar expression to identify it as a
forward-looking statement.

     WE CAUTION YOU THAT ANY SUCH FORWARD-LOOKING STATEMENTS ARE NOT GUARANTEES
OF FUTURE PERFORMANCE AND INVOLVE KNOWN AND UNKNOWN RISKS, UNCERTAINTIES AND
OTHER FACTORS WHICH MAY CAUSE OLD NATIONAL'S ACTUAL RESULTS, PERFORMANCE OR
ACHIEVEMENTS TO DIFFER MATERIALLY FROM THE FUTURE RESULTS, PERFORMANCE OR
ACHIEVEMENTS OLD NATIONAL HAS ANTICIPATED IN SUCH FORWARD-LOOKING STATEMENTS.

     In addition to the assumptions and other factors referred to specifically
in connection with their statements, factors that could cause Old National's
actual results to differ materially from those contemplated in the
forward-looking statements include factors Old National has described in the
"Management's Discussion and Analysis of Financial Condition and Results of
Operations" section of Old National's Annual Report on Form 10-K or in the other
documents Old National has incorporated by reference.

                                        2
<PAGE>   27

                      WHERE YOU CAN FIND MORE INFORMATION

     Old National files annual, quarterly and special reports, proxy statements
and other information with the SEC. Old National's SEC filings are available to
the public over the Internet at the SEC's web site at http://www.sec.gov. and
through Old National's own web site at http://oldnational.com. You may also read
and copy any document Old National files at the SEC's public reference rooms and
at the SEC's regional offices as follows:

<TABLE>
<S>                             <C>                             <C>
Public Reference Room           New York Regional Office        Chicago Regional Office
450 Fifth Street, N.W.          7 World Trade Center            Citicorp Center
Room 1024                       Suite 1300                      500 West Madison Street
Washington, D.C. 20549          New York, New York 10048        Suite 1400
                                                                Chicago, Illinois 60661-2551
</TABLE>

     You may also obtain copies of this information by mail from the Public
Reference Section of the SEC, 450 Fifth Street, N.W., Room 1024, Washington,
D.C. 20549, at prescribed rates. Further information on the operation of the
SEC's public reference room in Washington, D.C. can be obtained by calling the
SEC at 1-800-SEC-0330.

     The SEC allows Old National to "incorporate by reference" the information
Old National files with them, which means Old National is assumed to have
disclosed important information to you when Old National refers you to documents
that are on file with the SEC. The information Old National has incorporated by
reference is an important part of this prospectus, and information that Old
National files later with the SEC will automatically update and supersede this
information. Old National incorporates by reference the documents listed below
and any future documents Old National files with the SEC under Sections 13(a),
13(c), 14 or 15(d) of the Securities Exchange Act of 1934 until Old National
sells all of the securities covered by this prospectus.

     - Annual Report on Form 10-K for the fiscal year ended December 31, 1998.

     - Quarterly Reports on Form 10-Q for the quarters ended March 31, 1999,
       June 30, 1999 and September 30, 1999.

     - Current Report on Form 8-K filed on July 29, 1999, as amended.

     - Current Report on Form 8-K filed on December 1, 1999.

     You may request a copy of these documents at no cost by writing to Old
National at the following address:

                              Old National Bancorp
                                420 Main Street
                           Evansville, Indiana 47708
                           Attn: Corporate Controller
                           Telephone: (812) 464-1434

     You should rely only on the information provided in or incorporated by
reference (and not later changed) in this prospectus or any prospectus
supplement. Old National has not authorized anyone else to provide you with
additional or different information. Old National is not making an offer of any
securities in any state where the offer is not permitted. You should not assume
that the information in this prospectus or any prospectus supplement is accurate
as of any date other than the date on the front of those documents.

                                        3
<PAGE>   28

                              OLD NATIONAL BANCORP

     Overview. Old National is a bank holding company that operates 119 banking
offices and 174 ATM locations in Indiana, Illinois and Kentucky through its bank
subsidiaries. These banks provide a wide range of financial services, including:

     - commercial, consumer and real estate loans;

     - deposit products;

     - issuing and servicing credit cards;

     - leasing;

     - letters of credit; and

     - safe deposit facilities.

     Old National also owns non-bank subsidiaries that provide additional
financial services incidental to its operations, including:

     - securities brokerage services;

     - fiduciary and trust services;

     - investment services; and

     - issuance and reinsurance of credit life, accident, health, life, property
       and casualty insurance.

     Old National was incorporated in 1982 in the State of Indiana as the
holding company of the Old National Bank in Evansville, Indiana. Old National
Bank has provided banking services since 1834. Old National began an acquisition
program in 1985 and has acquired 38 financial institutions since that time. Old
National continues to explore opportunities to acquire banks, savings
associations and non-bank companies and is currently reviewing and analyzing
potential acquisitions, as well as engaging in discussions or negotiations
concerning potential acquisitions. There can be no assurance that any of these
discussions or negotiations will result in definitive agreements or consummated
acquisitions. Any acquisitions may be pending or completed during the period
that the capital securities are being offered.

     As a legal entity separate and distinct from its bank and non-bank
subsidiaries, Old National's principal sources of revenues are dividends and
fees from its bank and non-bank subsidiaries. The subsidiaries that operate in
the banking, insurance and securities business can pay dividends only if they
are in compliance with the applicable regulatory requirements imposed on them by
federal and state regulatory authorities. Old National currently believes that
none of these regulatory restrictions on the ability of its subsidiaries to pay
dividends will affect Old National's ability to service its debt.

     Old National's principal office is located at 420 Main Street, Evansville,
Indiana 47708, and its telephone number is (812) 464-1434.

     Supervision and Regulation. As a bank holding company, Old National is
subject to regulation, supervision and examination by the Board of Governors of
the Federal Reserve System under the Bank Holding Company Act of 1956, as
amended. For a discussion of certain of the material elements of the regulatory
framework applicable to bank holding companies and their subsidiaries and
certain specific information relevant to Old National, see Old National's Annual
Report on Form 10-K for the fiscal year ended December 31, 1998 which is
incorporated by reference into this prospectus.

     This regulatory framework is intended primarily for the protection of
depositors and the federal deposit insurance funds and not for the protection of
security holders or creditors. The various government rules, regulations and
requirements that apply to Old National impact its business and activities. A
change in applicable statutes, rules, regulations or regulatory policies may
have a material effect on Old National's

                                        4
<PAGE>   29

business and earnings. In addition, Old National's business and earnings are
affected by general economic conditions, legislation and actions of regulatory
authorities.

     Under policy of the Federal Reserve, a bank holding company is expected to
act as a source of financial strength for its bank subsidiaries and to commit
resources to support such banks. As a result, the Federal Reserve may require
Old National to commit resources to its bank subsidiaries.

                                 THE ONB TRUSTS

     Each ONB Trust is a statutory business trust that Old National has formed
under Delaware law. For each trust there is a trust agreement signed by Old
National as depositor, by Bank One Trust Company, NA, as property trustee, and
by Bank One Delaware, Inc., as Delaware trustee. For each trust there is also a
certificate of trust filed with the Delaware Secretary of State. When Old
National is ready to issue and sell securities through the trust, the trust
agreement will be amended to read substantially like the form of amended and
restated trust agreement that is filed with the SEC as an exhibit to the
registration statement of which this prospectus is a part. Each trust agreement
will be qualified as an indenture under the Trust Indenture Act of 1939.

THE ISSUANCE AND SALE OF THE CAPITAL SECURITIES AND COMMON SECURITIES

     Old National has created each ONB Trust solely to:

     - issue and sell its capital securities and common securities, which
       represent proportionate beneficial ownership interests in that ONB Trust
       and its assets;

     - use the proceeds from the sale of the capital securities and common
       securities to buy from Old National a series of Old National's junior
       subordinated debentures, which will be the only assets of that ONB Trust;

     - maintain its status as a grantor trust for federal income tax purposes;
       and

     - engage in only those other activities necessary or convenient to
       accomplish the purposes listed above.

     Because the ONB Trusts' only assets will be junior subordinated debentures
that Old National issues to them, Old National's payments on the junior
subordinated debentures will be the only source of funds to be paid to
purchasers or owners of the capital securities and common securities. Each of
the ONB Trusts is a separate legal entity, so the assets of one will not be
available to satisfy the obligations of any other similar trust Old National may
create.

     Old National will acquire and own all of the common securities of each ONB
Trust. The common securities will have an aggregate liquidation amount of at
least 3% of the total capital of each ONB Trust. The remainder, representing up
to 97% of the ownership interests in the ONB Trust, will be capital securities
of the ONB Trust that may be sold to the public. The common securities and the
capital securities will have substantially the same terms, including the same
priority of payment and liquidation amount, and will receive proportionate
payments from the ONB Trust in respect of distributions and payments upon
liquidation, redemption or otherwise at the same times, with one exception: if
Old National defaults on the junior subordinated debentures that it issues to
that ONB Trust and does not cure the default within the times specified in the
indenture governing the issuance of the junior subordinated debentures, Old
National's rights to payments as holder of the common securities will be
subordinated to the rights of the holders of the capital securities. See
"Description of Capital Securities -- Subordination of Common Securities."

     Unless Old National says otherwise in the applicable prospectus supplement,
each ONB Trust will have a term of approximately 50 years. However, an ONB Trust
may terminate earlier as provided in the applicable trust agreement and the
prospectus supplement.

                                        5
<PAGE>   30

     Each ONB Trust's business and affairs will be conducted by its trustees,
whom Old National, as holder of the common securities, will appoint. Unless Old
National says otherwise in the applicable prospectus supplement, the trustees
for each ONB Trust will be:

     - Bank One Trust Company, NA, as the property trustee; and

     - Bank One Delaware, Inc., as the Delaware trustee.

     Old National refers to the property trustee and the Delaware trustee
together as the "issuer trustees." Bank One Trust Company, NA, as property
trustee, will act as sole indenture trustee under each trust agreement for
purposes of compliance with the Trust Indenture Act. Unless Old National says
otherwise in the applicable prospectus supplement, Bank One Trust Company, NA
will also act as trustee under Old National's guarantee agreement relating to
the capital securities. See "Description of Guarantees" and "Description of Debt
Securities -- Certain Provisions Relating to Junior Subordinated Debentures
Issued to the ONB Trusts."

     As the holder of the common securities of each ONB Trust, Old National will
ordinarily have the right to appoint, remove or replace either issuer trustee
for each ONB Trust. However, if Old National is in default with respect to the
corresponding junior subordinated debentures issued to that ONB Trust (and Old
National has not cured that default within the time specified in the indenture),
then the holders of a majority in liquidation amount of that ONB Trust's
outstanding capital securities will be entitled to appoint, remove or replace
either or both issuer trustees. In no event will the holders of the capital
securities have the right to vote to appoint, remove or replace the
administrators. Old National retains that right exclusively as the holder of the
common securities. The duties and obligations of each issuer trustee are
governed by the applicable trust agreement.

     Pursuant to the indenture and the trust agreements, Old National promises
to pay all fees and expenses related to each ONB Trust and the offering of the
capital securities and will pay, directly or indirectly, all ongoing costs,
expenses and liabilities of each ONB Trust, except obligations under the capital
securities and the common securities.

     The ONB Trusts have no separate financial statements. Separate financial
statements would not be material to holders of the capital securities because
the ONB Trusts have no independent operations. They exist solely for the limited
functions summarized above. Old National will guarantee the capital securities
as described later in this prospectus.

     The principal executive office of each ONB Trust is c/o Old National
Bancorp, 420 Main Street, Evansville, Indiana 47708, and its telephone number is
(812) 464-1434.

                                USE OF PROCEEDS

     Each ONB Trust will use all of the proceeds it receives from the sale of
its capital securities and common securities to purchase from Old National the
junior subordinated debentures that will provide the funds for that ONB Trust's
payments to purchasers of its capital securities and common securities. Except
as otherwise described in the applicable prospectus supplement, Old National
intends to use the net proceeds from the sale of Old National's debt securities
(either to the ONB Trusts or directly to the public) for repayment of debt,
repurchases of its common stock, investments in and advances to its
subsidiaries, and general corporate purposes, including possible future
acquisitions. Old National may temporarily invest any funds not required
immediately for those purposes in short-term marketable securities. Old National
expects to borrow money or sell securities in the future, but Old National
cannot predict the precise amounts or timing of doing so. For current
information, look at Old National's current filings with the SEC. See "Where You
Can Find More Information."

                                        6
<PAGE>   31

                                 CAPITALIZATION

     The following table summarizes Old National's historical capitalization as
of September 30, 1999, and Old National's capitalization as adjusted to reflect
the assumed issuance and sale of an aggregate of $200 million liquidation amount
of capital securities and the related common securities of the trusts.

<TABLE>
<CAPTION>
                                                                  SEPTEMBER 30, 1999
                                                              --------------------------
                                                                ACTUAL      AS ADJUSTED
                                                              -----------   ------------
                                                              (IN THOUSANDS OF DOLLARS)
<S>                                                           <C>           <C>
Long term debt..............................................  $  774,259     $  774,259
Guaranteed Preferred Beneficial Interests in Company's
  Subordinated Debentures...................................          --        200,000
Shareholders' Equity
  Preferred stock, 2,000,000 shares authorized, no shares
     issued or outstanding..................................          --             --
  Common stock (no par value per share -- 75,000,000 shares
     authorized, and approximately 45,635,000 shares issued
     and outstanding).......................................  $   45,635     $   45,635
  Capital surplus...........................................     331,711        331,711
  Retained earnings.........................................     154,632        154,632
  Accumulated other comprehensive income, net of tax........     (17,043)       (17,043)
                                                              ----------     ----------
  Total shareholders' equity................................  $  514,938     $  514,938
                                                              ----------     ----------
Total capitalization........................................  $1,289,194     $1,489,194
                                                              ==========     ==========
Short term debt.............................................  $  560,673     $  560,673
</TABLE>

                       RATIO OF EARNINGS TO FIXED CHARGES

     Old National's historical ratios of earnings to fixed charges are described
below for the periods indicated.

<TABLE>
<CAPTION>
                                             NINE MONTHS
                                                ENDED
                                            SEPTEMBER 30,          YEAR ENDED DECEMBER 31,
                                            -------------   -------------------------------------
                                                1999        1998    1997    1996    1995    1994
                                            -------------   -----   -----   -----   -----   -----
<S>                                         <C>             <C>     <C>     <C>     <C>     <C>
Ratio of Earnings to Fixed Charges
  Excluding interest on deposits..........      2.94x       3.26x   3.68x   4.71x   4.38x   4.90x
  Including interest on deposits..........      1.53x       1.51x   1.51x   1.52x   1.48x   1.54x
</TABLE>

     The ratio of earnings to fixed charges for Old National has been computed
by dividing earnings by fixed charges. "Earnings" include pretax income from
continuing operations plus fixed charges. "Fixed charges" include the total of
interest expense, capitalized interest, expensed or capitalized amortization of
debt expense and any related discount or premium, and such portion of rental
expense that is representative of the interest factor of each such rental.

                         DESCRIPTION OF DEBT SECURITIES

     The debt securities, including any junior subordinated debentures that Old
National issues to an ONB Trust, will be Old National's direct unsecured general
obligations. The debt securities will be junior subordinated debt securities,
including the junior subordinated debentures that are issued to the ONB Trusts.
The debt securities will be issued in one or more series under the indenture
between Old National and Bank One Trust Company, NA, as trustee and under a
securities resolution of Old National authorizing the particular series.

     Old National has summarized selected provisions of the indenture below. The
summary is not complete. The form of the indenture and a form of amended and
restated trust agreement are filed as exhibits to the registration statement of
which this prospectus is a part. The amended and restated trust agreement for
each series also has been or will be filed or incorporated by reference as an
exhibit to the

                                        7
<PAGE>   32

registration statement. You should read the indenture and the applicable amended
and restated trust agreement for provisions that may be important to you. In the
summary below, Old National has included references to section numbers in the
indenture so that you can easily find those provisions. The particular terms of
any debt securities Old National offers will be described in the related
prospectus supplement, along with any applicable modifications of or additions
to the general terms of the debt securities described below and in the
indenture. For a description of the terms of any series of debt securities, you
should also review both the prospectus supplement relating to that series and
the description of the debt securities set forth in this prospectus before
making an investment decision.

GENERAL

     The indenture does not significantly limit Old National's operations. In
particular, it does not:

     - limit the amount of debt securities that Old National can issue under the
       indenture;

     - limit the number of series of debt securities that Old National can issue
       from time to time;

     - restrict the total amount of debt that Old National or its subsidiaries
       may incur; or

     - contain any covenant or other provision that is specifically intended to
       afford any holder of the debt securities special protection in the event
       of highly leveraged transactions or any other transactions resulting in a
       decline in Old National's ratings or credit quality.

     As of the date of this prospectus, there are no debt securities outstanding
under the indenture. The ranking of a series of debt securities with respect to
all of Old National's indebtedness will be established by the securities
resolution creating the series.

     Although the indenture permits the issuance of debt securities in other
forms or currencies, the debt securities covered by this prospectus will only be
denominated in U.S. dollars in registered form without coupons, unless otherwise
indicated in the applicable prospectus supplement.

TERMS

     A prospectus supplement and a securities resolution relating to the
offering of any series of debt securities will include specific terms relating
to the offering. The terms will include some or all of the following:

     - the designation, aggregate principal amount, currency or composite
       currency (if other than U.S. dollars) and denominations of the debt
       securities;

     - the price at which the debt securities will be issued and, if an index,
       formula or other method is used, the method for determining amounts of
       principal or interest;

     - the maturity date and other dates, if any, on which the principal of the
       debt securities will be payable;

     - the interest rate or rates, if any, or method of calculating the interest
       rate or rates which the debt securities will bear;

     - the date or dates from which interest will accrue and on which interest
       will be payable, and the record dates for the payment of interest; the
       manner of paying principal and interest on the debt securities; the place
       or places where principal and interest will be payable;

     - the terms of any mandatory or optional redemption of the debt securities
       by Old National, including any sinking fund, the terms of any conversion
       or exchange right; the terms of any redemption of debt securities at the
       option of holders; any tax indemnity provisions;

     - the portion of principal payable upon acceleration of the maturity date
       of any debt security;

                                        8
<PAGE>   33

     - whether and upon what terms debt securities may be defeased (which means
       that Old National would be discharged from its obligations by depositing
       sufficient cash or government securities to pay the principal, interest,
       any premiums and other sums due to the stated maturity date or a
       redemption date of the debt securities of the series);

     - whether any events of default or covenants in addition to or instead of
       those set forth in the indenture apply; provisions for electronic
       issuance of debt securities or for debt securities in uncertificated
       form;

     - any provisions relating to extending or shortening the date on which the
       principal and premium, if any, of the debt securities of the series is
       payable;

     - any provisions relating to the deferral of payment of any interest;

     - the terms of any right to convert or exchange the debt securities into
       any other securities or property of Old National;

     - if the series of debt securities is to be issued to an ONB Trust, the
       forms of the related trust agreement and guarantee agreement;

     - the additions or changes, if any, to the indenture with respect to that
       series of debt securities to permit or facilitate the issuance of that
       series of debt securities to an ONB Trust; and

     - any other terms not inconsistent with the provisions of the indenture,
       including any covenants or other terms that may be required or advisable
       under United States or other applicable laws or regulations, or advisable
       in connection with the marketing of the debt securities. (Section 3.1).

     Old National may issue debt securities of any series in such form and in
such denominations as Old National specifies in the securities resolution and
prospectus supplement for the series. (Section 2.1).

     A holder of registered debt securities may request registration of a
transfer upon surrender of the debt security being transferred at any agency or
office that Old National maintains for that purpose and upon fulfillment of all
other requirements of the agent.

CERTAIN COVENANTS

     Any restrictive covenants that may apply to a particular series of debt
securities will be described in the related prospectus supplement.

SUBORDINATION

     The indenture provides that the debt securities will be subordinated and
junior in right of payment to all Senior Debt (as defined below) of Old
National. This means that no payment of principal, including redemption
payments, premium, if any, or interest on the debt securities may be made if:

     - any Senior Debt of Old National has not been paid when due and any
       applicable grace period relating to such default has ended and such
       default has not been cured or waived or ceased to exist; or

     - the maturity of any Senior Debt of Old National has been accelerated
       because of a default.

     Upon any distribution of Old National's assets to creditors upon any
termination, winding-up, liquidation or reorganization, whether voluntary or
involuntary, or in bankruptcy, insolvency, receivership or other proceedings,
all principal, premium, if any, and interest due or to become due on all Senior
Debt of Old National must be paid in full before the holders of debt securities
are entitled to receive or retain any payment. Upon satisfaction of all claims
related to all Senior Debt of Old National then outstanding, the rights of the
holders of the debt securities will be subrogated to the rights of the holders
of Senior Debt of Old National to receive payments or distributions applicable
to Senior Debt until all amounts owing on the debt securities are paid in full.
                                        9
<PAGE>   34

     The term "Senior Debt" means:

          (1) the principal, premium, if any, and interest in respect of (a)
     indebtedness for money borrowed and (b) indebtedness evidenced by
     securities, notes, debentures, bonds or other similar instruments issued by
     Old National;

          (2) all capital lease obligations of Old National;

          (3) all obligations of Old National issued or assumed as the deferred
     purchase price of property, all conditional sale obligations of Old
     National and all obligations of Old National under any conditional sale or
     title retention agreement, but excluding trade accounts payable arising in
     the ordinary course of business;

          (4) all obligations, contingent or otherwise, of Old National in
     respect of any letters of credit, banker's acceptance, security purchase
     facilities or similar credit transactions;

          (5) all obligations in respect of interest rate swap, cap or other
     agreements, interest rate future or option contracts, currency swap
     agreements, currency future or option contracts and other similar
     agreements;

          (6) any indebtedness between or among Old National and its affiliates,
     except as provided in 8(b) below;

          (7) all obligations of the type referred to in clauses (1) through (6)
     above of other persons for the payment of which Old National is responsible
     or liable as obligor, guarantor or otherwise; and

          (8) all obligations of the type referred to in clauses (1) through (7)
     above of other persons secured by any lien on any property or asset of Old
     National, whether or not such obligation is assumed by such obligor, except
     for

             (a) any such indebtedness that by its terms ranks equally with, or
        junior to, the debt securities; and

             (b) any indebtedness between or among Old National and its
        affiliates relating to other debt securities and guarantees in respect
        of those debt securities issued to (i) any ONB Trust or a trustee of
        such ONB Trust or (ii) any other trust, or a trustee of such trust,
        partnership or other entity affiliated with Old National that is a
        financing vehicle of Old National in connection with the issuance by
        such financing vehicle of preferred securities or other securities
        guaranteed by Old National pursuant to an instrument that ranks equally
        with, or junior to, the guarantee.

     Such Senior Debt shall continue to be Senior Debt and be entitled to the
benefits of the subordination provisions irrespective of any amendment,
modification or waiver of any term of such Senior Debt.

SUCCESSOR OBLIGOR

     The indenture provides that, unless otherwise specified in the securities
resolution establishing a series of debt securities, Old National will not
consolidate with or merge into, or transfer all or substantially all of Old
National's assets to, another company, unless:

     - that company is organized under the laws of the United States or any
       state or the District of Columbia;

     - that company assumes by supplemental indenture all of Old National's
       obligations under the indenture and the debt securities;

     - all required approvals of any regulatory body having jurisdiction over
       the transaction shall have been obtained; and

     - immediately after the transaction no default exists under the indenture.
       (Section 8.1).

                                       10
<PAGE>   35

     The successor shall be substituted for Old National as if it had been an
original party to the indenture, the trust agreements and the debt securities.
Thereafter the successor may exercise Old National's rights and powers under the
indenture, the trust agreements and the debt securities, and all of Old
National's obligations under those documents will terminate. (Section 8.2)

EXCHANGE OF DEBT SECURITIES

     Registered debt securities may be exchanged for an equal principal amount
of registered debt securities of the same series and date of maturity in
authorized denominations requested by the holders upon surrender of the
registered debt securities at an office or agency Old National maintains for
that purpose and upon fulfillment of all other requirements set forth in the
indenture. (Section 3.6)

DEFAULTS

     Unless the securities resolution establishing the series provides for
different events of default, in which event the prospectus supplement will
describe the change, an event of default with respect to a series of debt
securities will occur if:

     - Old National defaults in any payment of interest on any debt securities
       of that series when the payment becomes due and payable and the default
       continues for a period of 30 days;

     - Old National defaults in the payment of the principal and premium, if
       any, of any debt securities of the series when those payments become due
       and payable at maturity or upon redemption, acceleration or otherwise;

     - Old National defaults in the payment or satisfaction of any sinking fund
       obligation with respect to any debt securities of the series as required
       by the securities resolution establishing the series and the default
       continues for a period of 30 days;

     - Old National defaults in the performance of any of Old National's other
       agreements applicable to the series and the default continues for 90 days
       after the notice specified below;

     - Old National files for bankruptcy or other specified events in
       bankruptcy, insolvency, receivership or reorganization occur; or

     - any other event of default specified in the prospectus supplement occurs.
       (See Section 5.1)

     A default under the indenture means any event which is, or after notice or
passage of time would be, an event of default under the indenture. A default
under the fourth bullet point above is not an event of default until the trustee
or the holders of at least 25% in principal amount of the debt securities of a
series notify Old National of the default and Old National does not cure the
default within the time specified after receipt of the notice. (Section 5.1)

REMEDIES

     If an event of default occurs under the indenture with respect to any
series of debt securities and is continuing, the trustee by notice to Old
National or (except as provided in the next sentence) the holders of at least
25% in principal amount of the series by notice both to Old National and to the
trustee, may declare the principal of and accrued interest on all the debt
securities of the series to be due and payable immediately. In the case of a
series of junior subordinated debentures issued to an ONB Trust, if, upon an
event of default, the trustee or the other holders, if any, together holding not
less than 25% in aggregate principal amount of that series, fail to declare the
principal of all the debt securities of that series to be immediately due and
payable, then the holders of 25% in aggregate liquidation amount of the capital
securities issued by the ONB Trust then outstanding shall have the right to do
so by notice to Old National and to the trustee.

                                       11
<PAGE>   36

     Except as provided in the next sentence, the holders of a majority in
principal amount of a series of debt securities, by notice to the trustee, may
rescind an acceleration and its consequences if certain conditions are met,
including:

          (a) Old National pays or deposits with the indenture trustee a sum
     sufficient to pay:

             (i) all overdue interest,

             (ii) the principal of and any premium which have become due other
        than by the declaration of acceleration and overdue interest on those
        amounts,

             (iii) any overdue sinking fund payments and overdue interest on
        such payments,

             (iv) interest on overdue interest to the extent lawful, and

             (v) all amounts otherwise due to the indenture trustee under the
        indenture;

          (b) the rescission would not conflict with any judgment or decree;

          (c) all existing events of default on the series have been cured or
     waived except nonpayment of principal or interest that has become due
     solely because of the acceleration.

     In the case of a series of junior subordinated debentures issued to an ONB
Trust, the holders of a majority in aggregate liquidation amount of the capital
securities issued by that ONB Trust then outstanding shall also have the right
to rescind the acceleration and its consequences with respect to such series,
subject to the same conditions set forth above. (Section 5.2)

     If an event of default occurs and is continuing on a series, the trustee
may pursue any available remedy to collect principal or interest then due on the
series, to enforce the performance of any provision applicable to the series, or
otherwise to protect the rights of the trustee and holders of the series.
(Section 5.3)

     In the case of a series of junior subordinated debentures issued to an ONB
Trust, any holder of the outstanding capital securities issued by that ONB Trust
shall have the right, upon the occurrence and continuance of an event of default
with respect to that series following Old National's failure to pay timely
interest, principal or premium as described above, to sue Old National directly.
In that lawsuit the holder of the capital securities can force Old National to
pay to the holder (instead of the ONB Trust) the principal of, and premium, if
any, and interest on, junior subordinated debentures held by the ONB Trust
having a principal amount equal to the aggregate principal amount of the capital
securities held by that holder. (Section 5.8)

     The trustee may require an indemnity satisfactory to it before it performs
any duty or exercises any right or power under the indenture or the debt
securities which it reasonably believes may expose it to any risk of loss or
liability. (Section 6.1) With some limitations, holders of a majority in
principal amount of the debt securities of a series may direct the trustee in
its exercise of any trust or power with respect to that series. (Section 5.12)
Except in the case of default in payment on a series, the trustee may withhold
notice of any continuing default with respect to the debt securities of that
series if it determines that withholding the notice is in the interest of
holders of the series. (Section 6.2) Old National is required to furnish the
trustee annually a brief certificate as to Old National's compliance with all
terms and conditions of the indenture. (Section 10.4)

     The events of default specified in the indenture do not include a
cross-default provision. Thus, except to the extent provided in the securities
resolution establishing a series, a default by Old National on any other debt,
including any other series of debt securities, would not constitute an event of
default under the indenture (or in the case of an event of default as to any
series, an event of default as to any other series outstanding under the
indenture). If a securities resolution provides for a cross-default provision,
the prospectus supplement will describe the terms of that provision.

                                       12
<PAGE>   37

AMENDMENTS

     Without the consent of any debt security holder, subject to certain
limitations, Old National may amend the indenture by entering into one or more
supplemental indentures for any of the following purposes:

     - to cure any ambiguity, omission, defect or inconsistency;

     - to provide for the assumption of Old National's obligations to debt
       security holders by the surviving company in the event of a merger or
       consolidation requiring such assumption as described above under
       "-- Successor Obligor";

     - to provide that specific provisions of the indenture shall not apply to a
       series of debt securities not previously issued;

     - to create a series of debt securities and establish its terms;

     - to provide for a separate trustee for one or more series of debt
       securities; or

     - to make any change that does not materially adversely affect the rights
       of any debt security holder. (Section 9.1)

     Unless the securities resolution provides otherwise, in which event the
prospectus supplement will describe the revised provision, Old National and the
trustee may amend the indenture by entering into one or more supplemental
indentures with the written consent of the holders of a majority in principal
amount of the debt securities of all series affected voting as one class.
However, without the consent of each debt security holder affected, no amendment
may:

     - reduce the principal amount of debt securities whose holders must consent
       to an amendment or waiver;

     - reduce the interest on or change the time for payment of interest on any
       debt security (but this does not affect Old National's right to elect to
       defer one or more payments of interest as described below under
       "-- Certain Provisions Relating to Junior Subordinated Debentures Issued
       to the ONB Trusts -- Option to Defer Interest Payment Date");

     - change the stated maturity of any debt security (subject to any right Old
       National may have retained in the securities resolution and described in
       the prospectus supplement);

     - reduce the principal of any debt security or, if less than the principal
       amount thereof, reduce the amount that would be due on acceleration of
       any debt security thereof;

     - change the currency in which the principal or interest on a debt security
       is payable;

     - make any change that materially adversely affects the right to convert or
       exchange any debt security; or

     - waive any default in payment of interest on or principal of a debt
       security. (Section 9.2)

     In the case of a series of junior subordinated debentures issued to an ONB
Trust, Old National is not permitted to amend the indenture if such amendment
adversely affects the holders of the capital securities of that ONB Trust in any
material respect, and no termination of the indenture shall occur, without the
prior consent of the holders of not less than a majority in aggregate
liquidation amount of the capital securities then outstanding unless and until
the principal (and premium, if any) of the junior subordinated debentures of
that series and all accrued and unpaid interest thereon have been paid in full.
Furthermore, in the case of a series issued to an ONB Trust, no amendment can be
made to the provisions of the indenture allowing holders of capital securities
of that ONB Trust to sue directly following Old National's failure to make
timely payments on the junior subordinated debentures as described above without
the prior consent of the holder of each capital security then outstanding unless
and until the principal (and

                                       13
<PAGE>   38

premium, if any) of the junior subordinated debentures of that series and all
accrued and unpaid interest thereon have been paid in full. (Section 9.2)

LEGAL DEFEASANCE AND COVENANT DEFEASANCE

     Debt securities of a series may be defeased at any time in accordance with
their terms and as set forth in the indenture and described briefly below,
unless the securities resolution establishing the terms of the series provides
otherwise. Any defeasance may terminate all of Old National's obligations (with
limited exceptions) with respect to a series of debt securities and the
indenture ("legal defeasance"), or it may terminate only Old National's
obligations under any restrictive covenants which may be applicable to a
particular series ("covenant defeasance").

     Old National may exercise Old National's legal defeasance option even
though Old National has also exercised Old National's covenant defeasance
option. If Old National exercises the legal defeasance option with respect to a
series of debt securities, that series may not be accelerated because of an
event of default. (Section 4.2) If Old National exercises the covenant
defeasance option, that series of debt securities may not be accelerated by
reference to any restrictive covenants which may be applicable to that
particular series. (Section 4.3)

     To exercise either defeasance option as to a series of debt securities, Old
National must:

     - irrevocably deposit in trust (the "defeasance trust") with the trustee or
       another trustee money or U.S. government obligations;

     - deliver a certificate from a nationally recognized firm of independent
       accountants expressing their opinion that the payments of principal and
       interest when due on the deposited U.S. government obligations, without
       reinvestment, plus any deposited money without investment, will provide
       cash at the times and in the amounts necessary to pay the principal and
       interest when due on all debt securities of the series to maturity or
       redemption, as the case may be; and

     - comply with certain other conditions. In particular, Old National must
       obtain an opinion of tax counsel that the defeasance will not result in
       recognition of any gain or loss to holders for federal income tax
       purposes.

     U.S. government obligations are direct obligations of (a) the United States
or (b) an agency or instrumentality of the United States, the payment of which
is unconditionally guaranteed by the United States, and which, in either case
(a) or (b), have the full faith and credit of the United States of America
pledged for payment and which are not callable at the issuer's option. It also
includes certificates representing an ownership interest in such obligations.
(Section 4.4)

CERTAIN PROVISIONS RELATING TO JUNIOR SUBORDINATED DEBENTURES ISSUED TO THE ONB
TRUSTS

     General. The junior subordinated debentures that Old National issues to an
ONB Trust may be issued in one or more series under the indenture with terms
corresponding to the terms of a series of capital securities issued by that ONB
Trust. The principal amount of the junior subordinated debentures that Old
National issues to an ONB Trust will be equal to the aggregate stated
liquidation amount of the capital securities and common securities of that ONB
Trust. Concurrently with the issuance of each ONB Trust's capital securities,
each ONB Trust will invest the proceeds from the sale of the capital securities
and the consideration Old National pays for the common securities in a series of
corresponding junior subordinated debentures that Old National will issue to
that ONB Trust.

     The prospectus supplement will describe specific terms relating to the
offering of each series of junior subordinated debentures. See "Description Of
Debt Securities -- Terms."

                                       14
<PAGE>   39

     Unless otherwise specified in the applicable securities resolution, Old
National will covenant, as to each series of junior subordinated debentures:

     - to maintain, directly or indirectly, 100% ownership of the common
       securities of the ONB Trust to which the corresponding junior
       subordinated debentures have been issued (provided that certain
       successors which are permitted pursuant to the indenture may succeed to
       Old National's ownership of the common securities);

     - not to voluntarily terminate, wind-up or liquidate any ONB Trust, except:

      -- in connection with a distribution of the junior subordinated debentures
         to the holders of the capital securities in liquidation of the ONB
         Trust; or

      -- in connection with certain mergers, consolidations or amalgamations
         permitted by the related trust agreement; and

     - to use Old National's reasonable efforts, consistent with the terms and
       provisions of the related trust agreement, to cause such ONB Trust to
       remain classified as a grantor trust and not as an association taxable as
       a corporation for United States federal income tax purposes.

     For additional covenants relating to payment of expenses of the ONB Trusts,
see "Description of Capital Securities -- Payment of Expenses."

     Option to Defer Interest Payment Date. Unless otherwise stated in the
applicable prospectus supplement, Old National will have the right at any time
and from time to time during the term of any series of junior subordinated
debentures issued to an ONB Trust to defer payments of interest by extending the
interest payment period for a specified number of consecutive periods. No
deferral period may extend beyond the maturity date of that series of junior
subordinated debentures. Old National may pay at any time all or any portion of
the interest accrued to that point during a deferral period. At the end of the
deferral period or at a redemption date, Old National will be obligated to pay
all interest accrued and unpaid (together with interest on the unpaid interest
to the extent permitted by applicable law). United States federal income tax
consequences and special considerations applicable to any junior subordinated
debentures issued to an ONB Trust for which a deferral period has been elected
will be described in the applicable prospectus supplement. During any deferral
period, or while Old National is in default, Old National will be restricted in
its ability to make payments or incur obligations related to its capital stock
or debt securities ranking equal to or below the junior subordinated debentures.
See "-- Restrictions on Certain Payments."

     Prior to the termination of any deferral period, Old National may extend
the interest payment period, and, after the termination of any deferral period
and the payment of all amounts due, Old National may decide to begin a new
deferral period. However, the deferral period may not extend beyond the maturity
date of the junior subordinated debentures.

     If the trustee is the sole holder of the series of junior subordinated
debentures held by the ONB Trust, Old National will give the trustee and the
issuer trustees of the ONB Trust notice of Old National's selection of any
deferral period one business day prior to the earlier of:

     - the next date distributions on the capital securities are payable; or

     - the date the ONB Trust is required to give notice to the New York Stock
       Exchange (or other applicable self-regulatory organization) or to holders
       of its capital securities of the record date or the date any distribution
       on the capital securities is payable.

                                       15
<PAGE>   40

     If the property trustee is not the sole holder of the series of junior
subordinated debentures, Old National will give the holders of the junior
subordinated debentures notice of Old National's selection of any deferral
period ten business days prior to the earliest of:

     - the next interest payment date; or

     - the date upon which Old National is required to give notice to the New
       York Stock Exchange (or other applicable self-regulatory organization) or
       to holders of the junior subordinated debentures of the record or payment
       date of any related interest payment.

     Redemption. The junior subordinated debentures and the applicable
securities resolution will provide the terms upon which Old National can redeem
the junior subordinated debentures at Old National's option, and will specify a
date prior to which Old National will not be allowed to redeem the junior
subordinated debentures, and after which Old National will have the right to
redeem the junior subordinated debentures, in whole or in part, upon not less
than 30 days nor more than 60 days notice to the holder of the junior
subordinated debentures at a redemption price or prices stated in the applicable
prospectus supplement. In order to redeem the junior subordinated debentures of
any series held by an ONB Trust, Old National may need to obtain the prior
approval of the Board of Governors of the Federal Reserve System.

     If the junior subordinated debentures are redeemed only in part, they will
be redeemed pro rata or by lot or by any other method selected by the trustee.
If a partial redemption of the junior subordinated debentures would result in
delisting from any national securities exchange or other self-regulatory
organization on which the capital securities of the ONB Trust holding the junior
subordinated debentures are then listed, Old National will not be permitted to
effect a partial redemption and may only redeem the junior subordinated
debentures as a whole.

     Except as otherwise specified in the applicable prospectus supplement and
subject to the provisions of the applicable securities resolution, if a Tax
Event (as defined below), an Investment Company Event (as defined below) or a
Regulatory Capital Event (as defined below) in respect of an ONB Trust occurs
and is continuing, Old National has the option to redeem the junior subordinated
debentures held by that ONB Trust, in whole, but not in part, at any time within
90 days thereafter. If the applicable ONB Trust is the holder of all outstanding
junior subordinated debentures, the proceeds of the redemption will be used by
the ONB Trust to redeem its capital securities and common securities in
accordance with their terms.

     However, in the case of an occurrence of a Tax Event, an Investment Company
or a Regulatory Capital Event, if Old National can eliminate, within the 90 day
period, such event by taking some action, such as filing a form or making an
election, or pursuing some other similar reasonable measure which has no adverse
effect on Old National, the relevant ONB Trust or the holders of the capital
securities or the common securities, Old National will pursue that action
instead of redemption. Old National will have no right to redeem the junior
subordinated debentures while such ONB Trust or the property trustee is pursuing
any similar action based on its obligations under the trust agreement.

     "Tax Event" means that the applicable ONB Trust will have received an
opinion of counsel (which may be counsel to Old National or an affiliate)
experienced in such matters to the effect that, as a result of any

     - amendment to, or change (including any announced proposed change) in the
       laws or any regulations under the laws of the United States or any
       political subdivision or taxing authority, or

     - official administrative pronouncement or judicial decision interpreting
       or applying the laws or regulations stated above whether or not the
       pronouncement or decision is issued to or in connection with a proceeding
       involving Old National or the ONB Trust,

                                       16
<PAGE>   41

in each case which amendment or change is effective or which proposed change,
pronouncement, action or decision is announced on or after the date of issuance
of the applicable series of junior subordinated debentures pursuant to the
applicable securities resolution, there is more than an insubstantial risk that:

     - the ONB Trust is, or will be within 90 days of the date of the opinion of
       counsel, subject to United States Federal income tax with respect to
       income received or accrued on the junior subordinated debentures;

     - interest Old National pays on the corresponding junior subordinated
       debentures is not, or will not be within 90 days of the date of the
       opinion of counsel, deductible, in whole or in part, for United States
       Federal income tax purposes; or

     - the ONB Trust is, or will be within 90 days of the date of the opinion of
       counsel, subject to more than a de minimis amount of other taxes, duties
       or other governmental charges.

     "Investment Company Event" means that the applicable ONB Trust will have
received an opinion of counsel experienced in such matters to the effect that,
as a result of the occurrence of a change in law or regulation or a change in
interpretation or application of law or regulation by any legislative body,
courts, governmental agency or regulatory authority on or after the date of
original issuance of the capital securities by the ONB Trust, the ONB Trust is
or will be considered an "investment company" that is required to be registered
under the Investment Company Act of 1940, as amended.

     "Regulatory Capital Event" means that if Old National determines, based on
an opinion of counsel experienced in such matters, who may be an employee of Old
National or any of Old National's affiliates, that, as a result of:

     - any amendment to, clarification of or change in applicable laws or
       regulations or official interpretations thereof or policies with respect
       thereto, or

     - any official administrative pronouncement or judicial decision
       interpreting or applying such laws or regulations,

there is more than an insubstantial risk that the capital securities will not
longer constitute Tier I Capital of Old National or any bank holding company of
which Old National is a subsidiary for purposes of the capital adequacy
guidelines or policies of the Board of Governors of the Federal Reserve System
or its successor as Old National's primary federal banking regulator.

     Restrictions on Certain Payments. Unless otherwise provided in the
applicable prospectus supplement, Old National will promise, as to each series
of junior subordinated debentures issued to an ONB Trust, that it will not:

     - declare or pay any dividends or distributions on, or redeem, purchase,
       acquire, or make a liquidation payment with respect to, any of its
       capital stock;

     - make any payment of principal, interest or premium, if any, on or repay,
       repurchase or redeem any of its debt securities (including other junior
       subordinated debentures) that rank equally with or junior in interest to
       the junior subordinated debentures; or

     - make any guarantee payments with respect to any of the debt securities of
       any of its subsidiaries if the guarantee ranks equally with or junior in
       interest to the junior subordinated debentures;

other than:

     - dividends or distributions payable in its common stock;

     - payments under any guarantee relating to the capital securities of an ONB
       Trust;

     - purchases of common stock related to the issuance of common stock under
       any benefit plans for its directors, officers or employees; and

                                       17
<PAGE>   42

     - obligations under any dividend reinvestment plan or stock purchase plan.

These restrictions apply only if:

     - at that time an event has occurred that (a) with the giving of notice or
       the lapse of time, or both, would constitute an event of default under
       the indenture with respect to the junior subordinated debentures of that
       series and (b) Old National shall not have taken reasonable steps to cure
       the event;

     - the junior subordinated debentures are held by an ONB Trust and Old
       National is in default with respect to payment of any obligations under
       the guarantee relating to the capital securities of that ONB Trust; or

     - Old National shall have given notice of its intention to begin an
       interest deferral period and have not rescinded the notice, or any
       deferral period is continuing.

REGARDING THE TRUSTEE

     Bank One Trust Company, NA will act as trustee and registrar for
registration and transfer of debt securities issued under the indenture.
(Section 3.6) The trustee, in its individual or any other capacity, may make
loans to, accept deposits from, and perform services for Old National or its
affiliates, and may otherwise deal with Old National or its affiliates, as if it
were not the trustee.

                       DESCRIPTION OF CAPITAL SECURITIES

     The following section describes the general terms and provisions of the
capital securities to which any prospectus supplement may relate. The particular
terms of the capital securities offered by any ONB Trust and the extent to which
any of these general provisions do not apply to its capital securities will be
described in the prospectus supplement relating to that ONB Trust and its
capital securities.

     The capital securities will represent undivided beneficial ownership
interests in the assets of an ONB Trust. The holders of the capital securities
of an ONB Trust will be entitled to a preference over holders of the common
securities of such ONB Trust in certain circumstances with respect to
distributions and amounts payable on redemption or liquidation. Holders of
capital securities will also have certain other benefits as described in the
corresponding trust agreement.

     Old National has summarized selected provisions of the capital securities
and each trust agreement below. This summary is not complete. The form of trust
agreement has been filed as an exhibit to the registration statement of which
this prospectus forms a part. You should read the form of trust agreement for
provisions that may be important to you. You should also consider applicable
provisions of the Trust Indenture Act. Each of the ONB Trusts is a legally
separate entity, and the assets of one are not available to satisfy the
obligations of the other.

GENERAL

     The capital securities of a ONB Trust will rank equally, and payments on
the capital securities will be made pro rata, with the common securities of that
ONB Trust except as described under "-- Subordination of Common Securities."
Legal title to the junior subordinated debentures issued to an ONB Trust will be
held by the property trustee in trust for the benefit of the holders of the
capital securities of that ONB Trust and for Old National as holder of the
common securities of that ONB Trust. Each guarantee agreement Old National
executes for the benefit of the holders of an ONB Trust's capital securities
will be a guarantee on a junior subordinated basis with, but will not guarantee
payment of distributions or amounts payable on redemption or liquidation of,
such capital securities if the ONB Trust does not have funds available to make
such payments. See "Description of Guarantees."

                                       18
<PAGE>   43

DISTRIBUTIONS

     Distributions on the capital securities will be cumulative, will accumulate
from the date of original issuance and will be payable on the dates specified in
the applicable prospectus supplement. Except as specified in the applicable
prospectus supplement, in the event that any date on which distributions are
payable on the capital securities is not a business day, payment of the
distribution will be made on the next succeeding day that is a business day
(without any interest or other payment in respect of the delay), with the same
force and effect as if made on the originally specified date. However, if the
next business day is in the next calendar year, payment of distributions will be
made on the preceding business day. Each date on which distributions are payable
is referred to in this prospectus as a distribution date.

     An ONB Trust's capital securities represent undivided beneficial ownership
interests in the assets of that ONB Trust. The distributions on each capital
security will be payable at a rate specified in the prospectus supplement for
that capital security. The amount of distributions payable for any period will
be computed on the basis of a 360-day year of twelve 30-day months unless
otherwise specified in the applicable prospectus supplement. Distributions to
which holders of capital securities are entitled will accumulate interest at the
rate per annum specified in the applicable prospectus supplement. Distributions
on capital securities as used in this prospectus includes these additional
distributions unless otherwise stated.

     The revenue of each ONB Trust available for distribution to holders of its
capital securities will be limited to payments it receives from Old National
under the junior subordinated debentures it owns. Each ONB Trust will invest the
proceeds from the issuance and sale of its common securities and capital
securities in the corresponding junior subordinated debentures, and it will have
no other assets. See "Description of Debt Securities -- Certain Provisions
Relating to Junior Subordinated Debentures Issued to the ONB Trusts." If Old
National does not make interest payments on the junior subordinated debentures
held by an ONB Trust, the property trustee will not have funds available to pay
distributions on the capital securities of that ONB Trust. Old National has
guaranteed the payment of distributions (if and to the extent the ONB Trust has
funds legally available for the payment of distributions and cash sufficient to
make the payments) on a limited basis as set forth herein under "Description of
Guarantees."

     Old National may defer interest on any series of junior subordinated
debentures for a specified number of consecutive interest payment periods. See
"Description of Debt Securities -- Certain Provisions Relating to Junior
Subordinated Debentures Issued to the ONB Trustee -- Option to Defer Interest
Payment Date." If Old National defers interest payments on the corresponding
junior subordinated debentures held by an ONB Trust, the ONB Trust will defer
payments on its capital securities.

     Distributions on the capital securities will be payable to the holders as
they appear on the register of the ONB Trust on the relevant record dates,
which, as long as the capital securities remain in book-entry form, will be one
business day prior to the relevant distribution date. Subject to any applicable
laws and regulations and to the provisions of the applicable trust agreement,
each distribution payment will be made as described under "Book-Entry Issuance."
In the event any capital securities are not in book-entry form, the relevant
record date for such capital securities shall be a date at least 15 days prior
to the relevant distribution date, as specified in the applicable prospectus
supplement.

PAYMENT OF EXPENSES

     Pursuant to the indenture, Old National has agreed to pay all debts and
obligations (other than distributions on the common securities and capital
securities) and all costs and expenses of the ONB Trusts and to pay any and all
taxes, duties, assessments or other governmental charges (other than United
States withholding taxes) imposed by the United States or any other taxing
authority. This includes, but is not limited to, all costs and expenses relating
to the organization of the ONB Trusts, the fees and expenses of the property
trustee, the Delaware trustee and the administrators and all costs and expenses
relating to the operation of the ONB Trusts. As a result, the net amounts
received and retained by an ONB Trust after paying these fees, expenses, debts
and obligations will be equal to the amounts the ONB Trust would have received
and retained had no fees, expenses, debts and obligations been incurred
                                       19
<PAGE>   44

by or imposed on it. Old National's promise to pay these obligations is for the
benefit of, and shall be enforceable by, any creditor to whom the fees,
expenses, debts and obligations are owed, whether or not the creditor has
received notice of the promise. Any creditor may enforce these obligations
directly against Old National, and Old National has agreed to irrevocably waive
any right or remedy that would otherwise require that any creditor take any
action against the ONB Trust or any other person before proceeding against Old
National. Old National will execute such additional agreements as may be
necessary to give full effect to these promises.

REDEMPTION OR EXCHANGE

     If Old National repays or redeems, in whole or in part, any junior
subordinated debentures that have been issued to an ONB Trust, whether at
maturity or earlier, the proceeds from the repayment or redemption shall be
applied by the property trustee to redeem a like amount of the capital
securities and the common securities of that ONB Trust. The property trustee
will give you at least 30 but no more than 60 days notice, and the redemption
price will be equal to the sum of:

     - the aggregate liquidation amount of the capital securities and common
       securities being redeemed; plus

     - accumulated but unpaid distributions on to the redeemed capital
       securities and common securities to the date of redemption; plus

     - the related amount of the premium, if any, that Old National pays upon
       the concurrent redemption of corresponding junior subordinated
       debentures.

     See "Description of Debt Securities -- Certain Provisions Relating to
Junior Subordinated Debentures Issued to the ONB Trusts -- Redemption."

     If Old National is repaying or redeeming less than all of any series of
junior subordinated debentures held by an ONB Trust on a redemption date, then
the proceeds from the repayment or redemption shall be allocated to redeem the
capital securities and common securities issued by that ONB Trust, pro rata. The
amount of premium, if any, that Old National pays to redeem all or any part of
any series of junior subordinated debentures held by an ONB Trust will also be
allocated pro rata to the redemption of the capital securities and common
securities issued by that ONB Trust.

     Old National will have the right to redeem any series of junior
subordinated debentures:

     - subject to the conditions described under "Description of Debt
       Securities -- Certain Provisions Relating to Junior Subordinated
       Debentures Issued to the ONB Trusts -- Redemption"; or

     - as may be otherwise specified in the applicable prospectus supplement.

     Old National has the right to terminate an ONB Trust at any time and, after
satisfaction of any liabilities to creditors of that ONB Trust as provided by
applicable law, to cause the junior subordinated debentures owned by that ONB
Trust to be distributed to the holders of the capital securities and common
securities in liquidation of that ONB Trust.

     If provided in the applicable prospectus supplement, Old National will have
the right to extend or shorten the maturity of any series of junior subordinated
debentures at the time that Old National exercises Old National's right to elect
to terminate an ONB Trust and cause the junior subordinated debentures held by
that ONB Trust to be distributed to the holders of the capital securities and
common securities in liquidation of that ONB Trust. However, Old National can
extend the maturity only if the conditions specified in the applicable
prospectus supplement are met at the time the election is made and at the time
of the extension.

                                       20
<PAGE>   45

     After the liquidation date fixed for any distribution of junior
subordinated debentures to the holders of any series of capital securities:

     - that series of capital securities will no longer be deemed to be
       outstanding;

     - The Depository Trust Company ("DTC") or its nominee, as the record holder
       of the capital securities, will receive a registered global certificate
       or certificates representing the junior subordinated debentures to be
       delivered in the distribution;

     - Old National shall use its reasonable efforts to list the junior
       subordinated debentures on the New York Stock Exchange or on such other
       exchange, interdealer quotation system or self-regulatory organization as
       such capital securities are then listed; and

     - any certificates representing that series of capital securities not held
       by DTC or its nominee will be deemed to represent the junior subordinated
       debentures having a principal amount equal to the stated liquidation
       amount of that series of capital securities, bearing accrued and unpaid
       interest in an amount equal to the accrued and unpaid distributions on
       that series of capital securities until the certificates are presented to
       the administrators or their agent for transfer or reissuance.

     Old National cannot predict the market prices for the capital securities or
the junior subordinated debentures that may be distributed in exchange for
capital securities. As a result, the capital securities that an investor may
purchase, or the junior subordinated debentures that an investor may receive on
termination and liquidation of an ONB Trust, may trade at a lower price than the
investor paid to purchase the capital securities.

REDEMPTION AND EXCHANGE PROCEDURES

     Any capital securities that are redeemed on any redemption date will be
redeemed with the proceeds received by the ONB Trust from the contemporaneous
redemption of the junior subordinated debentures held by that ONB Trust.
Redemptions of the capital securities will be made and the redemption price will
be payable on each redemption date only to the extent that the related ONB Trust
has cash on hand available for the payment of such redemption price. See
"-- Subordination of Common Securities."

     If an ONB Trust gives a notice of redemption in respect of its capital
securities, then, by 12:00 noon, New York City time, on the redemption date, the
property trustee will deposit irrevocably with DTC funds sufficient to pay the
applicable redemption price to the extent funds are available. The property
trustee will give DTC irrevocable instructions and authority to pay the
redemption price to the holders of such capital securities. See "Book-Entry
Issuance." If the capital securities are no longer in book-entry form, the
property trustee, to the extent funds are available, will irrevocably deposit
with the paying agent for the capital securities funds sufficient to pay the
applicable redemption price and will give the paying agent irrevocable
instructions and authority to pay the redemption price to the holders of the
capital securities upon surrender of the certificates evidencing their capital
securities.

     Except as specified in the applicable prospectus supplement, in the event
that any date fixed for redemption of capital securities is not a business day,
then payment of the redemption price payable on such date will be made on the
next succeeding day which is a business day (and without any interest or other
payment in respect of any delay). However, if the next business day is in the
next calendar year, the redemption price will be payable on the preceding
business day. In the event that payment of the redemption price in respect of
capital securities called for redemption is improperly withheld or refused and
not paid either by the ONB Trust or by Old National pursuant to the guarantee as
described under "Description of Guarantees," then:

     - distributions on those capital securities will continue to accrue at the
       then applicable rate from the redemption date originally established by
       the ONB Trust for those capital securities to the date the redemption
       price is actually paid; and

                                       21
<PAGE>   46

     - the actual payment date will be the date fixed for redemption for
       purposes of calculating the redemption price.

     Payment of the redemption price on the capital securities and any
distribution of corresponding junior subordinated debentures to holders of
capital securities will be made to the applicable record holders thereof as they
appear on the register for the capital securities on the relevant record date.
The record date will be one business day prior to the relevant redemption date
or liquidation date, as applicable, except that if any capital securities are
not in book-entry form, the relevant record date for those capital securities
shall be a date at least 15 days prior to the redemption date or liquidation
date, as applicable, as specified in the applicable prospectus supplement.

     If an ONB Trust redeems less than all of its capital securities and common
securities, then the aggregate liquidation amount of capital securities and
common securities to be redeemed will be allocated pro rata between the capital
securities and the common securities based upon their respective aggregate
liquidation amounts. Within 60 days of the redemption date, the property trustee
will select the capital securities to be redeemed from among the outstanding
capital securities not previously called for redemption. The property trustee
may use any method of selection it deems to be fair and reasonable.

     Notice of any redemption will be mailed at least 30 days but not more than
60 days before the redemption date to each holder of capital securities or
common securities to be redeemed at the holder's registered address.

     Unless Old National defaults in payment of the redemption price on the
junior subordinated debentures, on and after the redemption date, interest
ceases to accrue on the junior subordinated debentures or portions thereof (and
distributions cease to accrue on the capital securities or portions thereof
issued by the ONB Trust that holds such junior subordinated debentures) called
for redemption.

     If notice of redemption has been given and funds deposited as required,
then upon the date of such deposit all rights of the holders of the capital
securities called for redemption will cease, except the right to receive the
redemption price, but without interest on the redemption price, and the capital
securities will cease to be outstanding.

SUBORDINATION OF COMMON SECURITIES

     Payment of distributions on, and the redemption price of, each ONB Trust's
capital securities and common securities, as applicable, generally shall be made
pro rata based upon their respective aggregate liquidation amounts. However, if
on any distribution date or redemption date an event of default with respect to
any junior subordinated debenture held by an ONB Trust has occurred and is
continuing, then:

     - We shall not pay any distribution on, or redemption price of, any of the
       ONB Trust's common securities, and we can not make any other payment on
       account of the redemption, liquidation or other acquisition of such
       common securities, unless

      -- all accumulated and unpaid distributions on all of the ONB Trust's
         outstanding capital securities are paid in full in cash for all
         distribution periods terminating on or prior to any payment on the
         common securities,

      -- in the case of a payment of the redemption price, the full amount of
         the redemption price on all of the ONB Trust's outstanding capital
         securities then called for redemption shall have been paid or provided
         for, and

      -- all funds available to the property trustee shall first be applied to
         the payment in full in cash of all distributions on, or redemption
         price of, the ONB Trust's capital securities then due and payable.

     In the case of any event of default with respect to any junior subordinated
debentures held by an ONB Trust, Old National (as holder of the ONB Trust's
common securities) will be deemed to have

                                       22
<PAGE>   47

waived any right to act with respect to the event of default under the
applicable trust agreement until the effect of all events of default with
respect to such capital securities has been cured, waived or otherwise
eliminated. Until any events of default under the applicable trust agreement
with respect to the capital securities have been cured, waived or otherwise
eliminated, the property trustee is required to act solely on behalf of the
holders of the capital securities and not on Old National's behalf as holder of
the ONB Trust's common securities, and only the holders of such capital
securities will have the right to direct the property trustee to act on their
behalf.

LIQUIDATION DISTRIBUTION UPON TERMINATION

     Pursuant to its respective trust agreement, each ONB Trust will
automatically terminate upon the expiration of its term or on the first to occur
of:

     - specified events relating to Old National's bankruptcy, dissolution or
       liquidation;

     - Old National's written direction to the property trustee, as depositor,
       to dissolve the ONB Trust and distribute the corresponding junior
       subordinated debentures to the holders of the capital securities in
       exchange for the capital securities (which direction is optional and
       wholly within Old National's discretion as depositor);

     - the redemption of all of the ONB Trust's capital securities and common
       securities; and

     - the entry of an order for the dissolution of the ONB Trust by a court of
       competent jurisdiction.

     If an early termination occurs for any reason other than the redemption of
all of the capital securities and common securities, the ONB Trust will be
liquidated by the property trustee as expeditiously as the issuer trustees
determine to be possible. Except as provided in the next sentence, the issuer
trustees will distribute (after satisfaction of any liabilities to creditors of
such ONB Trust as provided by applicable law) to the holders of such capital
securities and common securities a like amount of the corresponding junior
subordinated debentures. However, if such a distribution is determined by the
property trustee not to be practical, the holders of the capital securities will
be entitled to receive out of the assets of the ONB Trust available for
distribution to holders (after satisfaction of any liabilities to creditors of
the ONB Trust as provided by applicable law) a liquidation distribution in an
amount equal to the aggregate of the liquidation amount plus accrued and unpaid
distributions thereon to the date of payment. If the liquidation distribution
can be paid only in part because the ONB Trust has insufficient assets available
to pay in full the aggregate liquidation distribution, then the amounts payable
directly by the ONB Trust on its capital securities will be paid on a pro rata
basis.

     As the holder of the ONB Trust's common securities, Old National will be
entitled to receive distributions upon any liquidation pro rata with the holders
of its capital securities. However, if an event of default relating to the
junior subordinated debentures held by an ONB Trust has occurred and is
continuing, that ONB Trust's capital securities will have a priority over its
common securities.

ADDITIONAL AMOUNTS

     If at any time an ONB Trust is required to pay any taxes, duties,
assessments or governmental charges of whatever nature, other than withholding
taxes, imposed by the United States, or any other taxing authority, then Old
National will be required to pay additional amounts on the junior subordinated
debt securities. The additional amounts will be sufficient so that the net
amounts received and retained by the ONB Trust after paying any such taxes,
duties, assessments or other governmental charges will be not less than the
amounts the ONB Trust would have received had no such taxes, duties, assessments
or other governmental charges been imposed. This means that the ONB Trust will
be in the same position it would have been if it did not have to pay such taxes,
duties, assessments or other charges.

                                       23
<PAGE>   48

EVENTS OF DEFAULT; NOTICE

     Any one of the following events constitutes a "trust event of default"
under each trust agreement with respect to the capital securities issued by an
ONB Trust thereunder (whatever the reason for the trust event of default):

     - an event of default with respect to the junior subordinated debentures
       issued under the indenture to the ONB Trust occurs (see "Description of
       Debt Securities -- Defaults");

     - the property trustee does not pay any distribution within 30 days of its
       due date, provided that no deferral period is continuing;

     - the property trustee does not pay any redemption price of any trust
       security when it becomes due and payable;

     - the default by an issuer trustee in the performance, or breach, in any
       material respect, of any covenant or warranty of the issuer trustees in
       the trust agreement (other than a default in the payment of any
       distribution or any redemption price as provided above), and continuation
       of that default or breach for a period of 90 days after there has been
       given, by registered or certified mail, to the defaulting issuer trustee
       by the holders of at least 25% in aggregate liquidation preference of the
       outstanding capital securities of the applicable ONB Trust, a written
       notice specifying the default or breach and requiring it to be remedied
       and stating that the notice is a "notice of default" under the trust
       agreement; or

     - the property trustee files for bankruptcy or certain other events in
       bankruptcy or insolvency occur and a successor property trustee is not
       appointed within 60 days.

     Within 90 days after learning of the occurrence of any trust event of
default, the property trustee is required to transmit notice of the trust event
of default to the holders of the ONB Trust's capital securities, to the
administrators and to Old National, as depositor, unless the trust event of
default has been cured or waived.

     If an event of default with respect to a corresponding junior subordinated
debenture has occurred and is continuing, the capital securities shall have a
preference over the common securities upon termination of the ONB Trust as
described above. See "-- Liquidation Distribution upon Termination." The
existence of a trust event of default with respect to an ONB Trust does not
entitle the holders of capital securities issued by that ONB Trust to cause the
redemption of the capital securities.

REMOVAL OF ISSUER TRUSTEES

     Old National as the holder of the common securities of an ONB Trust may
remove either issuer trustee at any time, unless an event of default with
respect to junior subordinated debentures held by that ONB Trust has occurred
and is continuing. If a trust event of default resulting from an event of
default with respect to junior subordinated debentures held by that ONB Trust
has occurred and is continuing, the property trustee and the Delaware trustee
may be removed by the holders of a majority in liquidation amount of the
outstanding capital securities of that ONB Trust. In no event will the holders
of the capital securities have the right to vote to appoint, remove or replace
the administrators: that right belongs exclusively to Old National as the holder
of the common securities. No resignation or removal of an issuer trustee and no
appointment of a successor trustee will be effective until the successor trustee
accepts its appointment in accordance with the provisions of the applicable
trust agreement.

MERGER OR CONSOLIDATION OF ISSUER TRUSTEES

     Any corporation into which the property trustee or the Delaware trustee
that is not a natural person may be merged or converted or with which it may be
consolidated, or any corporation resulting from any merger, conversion or
consolidation to which such trustee shall be a party, or any corporation
succeeding

                                       24
<PAGE>   49

to all or substantially all the corporate trust business of such trustee, shall
be the successor of such trustee under each trust agreement, provided such
corporation shall be otherwise qualified and eligible.

MERGERS, CONSOLIDATIONS, CONVERSIONS, AMALGAMATIONS OR REPLACEMENTS OF THE ONB
TRUSTS

     An ONB Trust may not merge or consolidate with or into, convert into,
amalgamate or be replaced by, or convey, transfer or lease its properties and
assets substantially as an entirety to any corporation or other person, except
as described below, as described in "-- Liquidation Distribution upon
Termination" or as described in the prospectus supplement with respect to the
capital securities. An ONB Trust may, at Old National's request, with the
consent the holders of a majority of its capital securities, merge or
consolidate with or into, convert into, amalgamate or be replaced by or convey,
transfer or lease its properties and assets substantially as an entirety to a
trust organized as such under the laws of any state; provided, that:

     - the successor entity either (a) expressly assumes all of the obligations
       of the ONB Trust with respect to its capital securities or (b)
       substitutes for the capital securities other successor securities having
       substantially the same terms as the capital securities so long as the
       successor securities rank the same as the capital securities rank in
       priority with respect to distributions and payments upon liquidation,
       redemption and otherwise;

     - Old National expressly appoints a trustee of such successor entity
       possessing the same powers and duties as the property trustee as the
       holder of the corresponding junior subordinated debentures;

     - the successor securities are listed, or any successor securities will be
       listed upon notification of issuance, on any national securities exchange
       or other organization on which the capital securities are then listed, if
       any;

     - the merger, consolidation, conversion, amalgamation, replacement,
       conveyance, transfer or lease does not cause the capital securities
       (including any successor securities) to be downgraded by a nationally
       recognized statistical rating organization;

     - the merger, consolidation, conversion, amalgamation, replacement,
       conveyance, transfer or lease does not adversely affect the rights,
       preferences and privileges of the holders of the capital securities
       (including any successor securities) in any material respect;

     - the successor entity has a purpose substantially similar to that of the
       ONB Trust;

     - prior to the merger, consolidation, conversion, amalgamation,
       replacement, conveyance, transfer or lease, the property trustee has
       received an opinion from independent counsel to the ONB Trust experienced
       in such matters to the effect that:

      -- the merger, consolidation, conversion, amalgamation, replacement,
         conveyance, transfer or lease does not adversely affect the rights,
         preferences and privileges of the holders of the capital securities
         (including any successor securities) in any material respect, and

      -- following the merger, consolidation, conversion, amalgamation,
         replacement, conveyance, transfer or lease, neither the ONB Trust nor
         such successor entity will be required to register as an investment
         company under the Investment Company Act; and

     - Old National or any permitted successor or assignee owns all of the
       common securities of the successor entity and guarantees the obligations
       of the successor entity under the successor securities at least to the
       extent provided by the guarantee.

Notwithstanding the general provisions described above, an ONB Trust shall not,
except with the consent of holders of 100% in liquidation amount of the capital
securities, merge with or into, consolidate, convert into, amalgamate, or be
replaced by or convey, transfer or lease its properties and assets substantially
as an entirety to any other entity or permit any other entity to consolidate,
amalgamate, merge with or into, or replace it if such merger, consolidation,
conversion, amalgamation, replacement, conveyance, transfer or

                                       25
<PAGE>   50

lease would cause the ONB Trust or the successor entity to be classified as
other than a grantor trust for United States federal income tax purposes.

VOTING RIGHTS; AMENDMENT OF EACH TRUST AGREEMENT

     The holders of the capital securities will have only the voting rights
described below and under "Description of Guarantees -- Amendments and
Assignment," plus any voting rights required by law.

     Each trust agreement may be amended from time to time by Old National and
the property trustee, without the consent of the holders of the capital
securities:

     - to cure any ambiguity, correct or supplement any provisions in the trust
       agreement that may be inconsistent with any other provision, or to
       address matters or questions arising under the trust agreement in a way
       which is consistent with the other provisions of the trust agreement; or

     - to modify, eliminate or add to any provisions of the trust agreement if
       necessary to ensure that the ONB Trust will be classified for United
       States federal income tax purposes as a grantor trust or to ensure that
       the ONB Trust will not be required to register as an "investment company"
       under the Investment Company Act.

     However, in the case of the first clause, the action must not adversely
affect in any material respect the interests of any holder of capital securities
and common securities. Any amendment of the trust agreement becomes effective
when Old National gives notice of the amendment to the holders of the capital
securities and common securities.

     Each trust agreement may be amended by Old National and the property
trustee with:

     - the consent of holders representing not less than a majority (based upon
       liquidation amounts) of the outstanding capital securities and common
       securities; and

     - receipt by the property trustee of an opinion of counsel experienced in
       such matters to the effect that the amendment or the exercise of any
       power granted to the issuer trustees in accordance with the amendment
       will not affect the ONB Trust's status as a grantor trust for United
       States federal income tax purposes or the ONB Trust's exemption from
       status as an "investment company" under the Investment Company Act.

     However, without the consent of each holder of capital securities and
common securities, no amendment may:

     - change the amount or timing of any distribution on the capital securities
       and common securities or otherwise adversely affect the amount of any
       distribution required to be made in respect of the capital securities and
       common securities as of a specified date; or

     - restrict the right of a holder of capital securities and common
       securities to sue for the enforcement of any distribution payment.

     The property trustee is required to notify each holder of capital
securities whenever the property trustee is notified of a default with respect
to the corresponding junior subordinated debentures. Furthermore, so long as any
junior subordinated debentures are held by the property trustee, the issuer
trustees are not permitted to:

     - direct the time, method and place of conducting any proceeding for any
       remedy available to the trustee under the indenture, or execute any trust
       or power conferred on the property trustee with respect to the junior
       subordinated debentures;

     - waive any past default that is waivable under the indenture governing the
       junior subordinated debentures;

                                       26
<PAGE>   51

     - exercise any right to rescind or annul a declaration that the principal
       of all the junior subordinated debentures shall be due and payable; or

     - give a required consent to any amendment, modification or termination of
       the indenture, the applicable securities resolution or the junior
       subordinated debentures

unless, in each case, they first obtain the approval of the holders of a
majority in aggregate liquidation amount of all outstanding capital securities.
However, where the indenture requires the consent of each affected holder of
junior subordinated debentures, the property trustee cannot give the consent
without first obtaining the consent of each holder of the capital securities.
The property trustee cannot revoke any action previously authorized or approved
by a vote of the holders of the capital securities except by subsequent vote of
the holders of the capital securities.

     In addition to obtaining approval of the holders of the capital securities
as described above, the issuer trustees are required to obtain an opinion of
counsel to the effect that the proposed action will not cause the ONB Trust to
be classified as a corporation for United States federal income tax purposes.

     Any required approval of holders of capital securities may be given either
at a meeting of holders of capital securities or pursuant to a written consent.
The property trustee must notify record holders of capital securities of any
meeting in the manner set forth in each trust agreement.

     No vote or consent of the holders of capital securities will be required
for an ONB Trust to redeem and cancel its capital securities in accordance with
the applicable trust agreement.

     Whenever holders of capital securities are entitled to vote or consent
under any of the circumstances described above, neither Old National nor the
issuer trustees will be permitted to vote. For purposes of any vote or consent,
any of the capital securities that Old National owns (or that are owned by the
issuer trustees or Old National's affiliates) will be treated as if they were
not outstanding.

PAYMENT AND PAYING AGENCY

     The depositary for the capital securities will make payments in respect of
the capital securities by crediting the relevant accounts at the depositary on
the applicable distribution dates. If any capital securities of an ONB Trust are
not held by the depositary, then the paying agent will mail checks to registered
holders of the capital securities as their addresses appear on its register.
Unless otherwise specified in the applicable prospectus supplement, the paying
agent shall initially be the property trustee and any co-paying agent chosen by
the property trustee and acceptable to the administrators and to Old National.
The paying agent can resign upon 30 days' written notice to the property trustee
and to Old National. If the property trustee resigns as paying agent, the
property trustee will appoint a bank or trust company acceptable to the
administrators to act as paying agent.

REGISTRAR AND TRANSFER AGENT

     Unless otherwise specified in the applicable prospectus supplement, the
property trustee will act as registrar and transfer agent for the capital
securities.

     Each ONB Trust will register transfers of its capital securities without
charge, but will require payment of any tax or other governmental charges that
may be imposed in connection with any transfer or exchange. The ONB Trusts will
not register transfers of their capital securities after the relevant capital
securities are called for redemption.

INFORMATION CONCERNING THE PROPERTY TRUSTEE

     The property trustee undertakes to perform only the duties that are
specifically set forth in each trust agreement, other than during the
continuance of a trust event of default. After a trust event of default, the
property trustee is required to exercise the same degree of care and skill as a
prudent person would exercise or use in the conduct of his or her own affairs.
Subject to this provision, the property trustee has

                                       27
<PAGE>   52

no obligation to exercise any of its powers under the applicable trust agreement
at the request of any holder of capital securities unless it is offered
reasonable indemnity against the costs, expenses and liabilities that it might
incur by doing so. If no trust event of default has occurred and is continuing
and the property trustee is required to decide between alternative courses of
action, construe ambiguous provisions in the applicable trust agreement or is
unsure of the application of any provision of the applicable trust agreement,
then Old National will have the right to tell the property trustee which action
to take unless the matter is one on which holders of capital securities are
entitled to vote. If Old National doesn't give any directions, the property
trustee will take whatever action it deems advisable and in the best interests
of the holders of the capital securities and common securities. The property
trustee will have no liability except for its own bad faith, negligence or
willful misconduct.

MISCELLANEOUS

     The property trustee and the administrators are authorized and directed to
operate the ONB Trusts in such a way that:

     - no ONB Trust will be:

      -- deemed to be an "investment company" required to be registered under
         the Investment Company Act or

      -- classified as an association taxable as a corporation for United States
         federal income tax purposes; and

     - the junior subordinated debentures will be treated as Old National's
       indebtedness for United States federal income tax purposes.

     Holders of the capital securities have no preemptive or similar rights.

     No ONB Trust may borrow money or issue debt or mortgage or pledge any of
its assets.

                           DESCRIPTION OF GUARANTEES

     When the capital securities and common securities of any series are issued
by an ONB Trust, Old National will execute and deliver a guarantee agreement for
the benefit of the holders of the capital securities of that series. The
guarantee agreement will be qualified as an indenture under the Trust Indenture
Act. Bank One Trust Company, NA will act as guarantee trustee under each
guarantee for the purposes of compliance with the Trust Indenture Act, and will
hold the guarantee for the benefit of the holders of the related ONB Trust's
capital securities.

     Old National has summarized certain provisions of the guarantees below.
This summary is not complete. The form of the guarantee agreement has been filed
as an exhibit to the registration statement of which this prospectus forms a
part, and you should read the guarantee agreement for provisions that may be
important to you. Reference in this summary to capital securities means that ONB
Trust's capital securities to which a guarantee relates.

GENERAL

     Old National will promise to pay the guarantee payments to the holders of
the capital securities, as and when due, regardless of any defense, right of
set-off or counterclaim that the ONB Trust may have or assert other than the
defense of payment. Old National's obligations under the guarantee will rank
equal to the corresponding junior subordinated debentures and will be junior and
subordinated to the Senior Debt.

                                       28
<PAGE>   53

The guarantee payments include the following, to the extent not paid by or on
behalf of the related ONB Trust:

     - any accumulated and unpaid distributions required to be paid on the
       capital securities, but only if and to the extent that the applicable ONB
       Trust has funds on hand available for the distributions at that time;

     - the redemption price with respect to any capital securities called for
       redemption, if and to the extent that the applicable ONB Trust has funds
       on hand available to pay the redemption price at that time; or

     - upon a voluntary or involuntary termination, winding up or liquidation of
       an ONB Trust (unless the corresponding junior subordinated debentures are
       distributed to the holders of the capital securities), the lesser of:

      -- the liquidation distribution; and

      -- the amount of assets of the applicable ONB Trust remaining available
         for distribution to holders of capital securities.

     Old National's obligation to make a guarantee payment may be satisfied
either by Old National's direct payment of the required amounts to the holders
of the applicable capital securities or by causing the ONB Trust to pay them.

     Each guarantee will be an irrevocable guarantee on a junior subordinated
basis of the related ONB Trust's obligations in respect of the capital
securities, but will apply only to the extent that the related ONB Trust has
funds sufficient to make the required payments. If Old National does not make
interest payments on the junior subordinated debentures held by an ONB Trust,
the ONB Trust will not be able to pay distributions on its capital securities.

     Old National has also agreed to guarantee the obligations of the ONB Trusts
with respect to the common securities to the same extent as the guarantee to
holders of the capital securities. However, if there is an event of default with
respect to a corresponding junior subordinated debenture, holders of capital
securities issued by that ONB Trust will have priority over holders of common
securities issued by that ONB Trust.

STATUS OF THE GUARANTEES

     Each guarantee will constitute Old National's unsecured obligation and will
rank subordinate and junior in right of payment to all of Old National's Senior
Debt.

     Each guarantee will rank equally with all other guarantees Old National
issues relating to capital securities issued by the ONB Trusts. Each guarantee
will constitute a guarantee of payment and not of collection (i.e., the
guaranteed party may institute a legal proceeding directly against Old National
as the guarantor to enforce its rights under the guarantee without first suing
anyone else). Each guarantee will be held for the benefit of the holders of the
related capital securities. Each guarantee will be discharged only by payment of
the guarantee payments in full (to the extent not paid by the ONB Trust) or by
distribution of the corresponding junior subordinated debentures to the holders
of the capital securities. None of the guarantees places a limitation on the
amount of additional Senior Debt or subordinated debt that Old National may
incur. Old National expects from time to time to incur additional indebtedness
constituting Senior Debt.

AMENDMENTS AND ASSIGNMENT

     Except with respect to any changes which do not adversely affect the rights
of holders of the related capital securities in any material respect (in which
case no vote will be required), no guarantee may be amended without the prior
approval of the holders of not less than a majority of the aggregate liquidation
amount of the related outstanding capital securities. The manner of obtaining
any required approval will be
                                       29
<PAGE>   54

as set forth under "Description of Capital Securities -- Voting Rights;
Amendment of Each Trust Agreement." All guarantees and agreements contained in
each guarantee agreement will bind Old National's successors, assigns,
receivers, trustees and representatives and will benefit the holders of the
related capital securities then outstanding.

EVENTS OF DEFAULT

     Old National will be in default under any guarantee agreement if (a) Old
National doesn't make required payments or (b) Old National is notified that it
has not performed some other obligation and have not cured that failure within
90 days.

     The holders of a majority in aggregate liquidation amount of the related
capital securities have the right:

     - to direct the time, method and place of conducting any proceeding for any
       remedy available to the guarantee trustee in respect of the guarantee
       agreement; or

     - to direct the exercise of any power conferred upon the guarantee trustee
       under the guarantee agreement.

Holders of a majority in aggregate liquidation amount of the related capital
securities also have the right to waive any past event of default and its
consequences.

     Any holder of the capital securities may institute a legal proceeding
directly against Old National to enforce the ONB Trust's rights under the
guarantee agreement without first instituting a legal proceeding against the ONB
Trust, the guarantee trustee or anyone else.

     As guarantor, Old National is required to file annually with the guarantee
trustee a certificate stating whether or not Old National is in compliance with
all the conditions and covenants applicable to Old National under the guarantee
agreement.

INFORMATION CONCERNING THE GUARANTEE TRUSTEE

     The guarantee trustee will perform only the duties that are specifically
set forth in each guarantee agreement, other than during the occurrence and
continuance of a default by Old National in performance of any guarantee. After
Old National defaults and while the default continues, the guarantee trustee
must exercise the same degree of care and skill as a prudent person would
exercise or use in the conduct of his or her own affairs. Subject to this
provision and so long as no default under the applicable guarantee agreement has
occurred and is continuing, the guarantee trustee is under no obligation to
exercise any of the powers vested in it by any guarantee agreement at the
request of any holder of any capital securities unless it is offered reasonable
indemnity against the costs, expenses and liabilities that it might incur by
doing so.

TERMINATION OF THE GUARANTEES

     Each guarantee will terminate upon full payment of the redemption price of
the related capital securities, upon full payment of the amounts payable upon
liquidation of the related ONB Trust or upon distribution of corresponding
junior subordinated debentures to the holders of the related capital securities.
Each guarantee will continue to be effective or will be reinstated, as the case
may be, if at any time any holder of the related capital securities must restore
payment of any sums paid under the capital securities or the guarantee.

                                       30
<PAGE>   55

                   RELATIONSHIP AMONG THE CAPITAL SECURITIES,
                THE CORRESPONDING JUNIOR SUBORDINATED DEBENTURES
                               AND THE GUARANTEES

FULL AND UNCONDITIONAL GUARANTEE

     Old National irrevocably guarantees payments of distributions and other
amounts due on the capital securities (to the extent the applicable ONB Trust
has funds available for the payment of the distributions) as and to the extent
set forth under "Description of Guarantees." Taken together, Old National's
obligations under each series of junior subordinated debentures, the related
securities resolution, the indenture, the related trust agreement and the
related guarantee agreement provide, in the aggregate, a full, irrevocable and
unconditional guarantee of payments of distributions and other amounts due on
the related series of capital securities. No single document standing alone or
operating in conjunction with fewer than all of the other documents constitutes
the full guarantee. It is only the combined operation of these documents that
has the effect of providing a full, irrevocable and unconditional guarantee of
the ONB Trust's obligations under the capital securities. See "The ONB Trusts,"
"Description of Capital Securities," and "Description of Debt
Securities -- Certain Provisions Relating to Junior Subordinated Debentures
Issued to the ONB Trusts."

     If and to the extent that Old National does not make payments on any series
of corresponding junior subordinated debentures, the ONB Trust will not pay
distributions or other amounts due on its capital securities. The guarantees do
not cover payment of distributions when the related ONB Trust does not have
sufficient funds to pay the distributions. In that event, the remedy for a
holder of the capital securities issued by that trust is to institute a legal
proceeding directly against Old National for enforcement of payment of the
distributions to such holder. Old National's obligations under each guarantee
are subordinate and junior in right of payment to all of Old National's Senior
Debt.

SUFFICIENCY OF PAYMENTS

     As long as Old National makes payments when due on each series of junior
subordinated debentures, those payments will be sufficient to cover
distributions and other payments due on the related capital securities. This is
primarily because:

     - the aggregate principal amount of each series of junior subordinated
       debentures will be equal to the sum of the aggregate stated liquidation
       amount of the related capital securities and related common securities;

     - the interest rate and interest and other payment dates on each series of
       junior subordinated debentures will match the distribution rate and
       distribution and other payment dates for the related capital securities;

     - Old National, as issuer of the junior subordinated debentures, has
       promised to pay any and all costs, expenses and liabilities of each ONB
       Trust except the ONB Trust's obligations under its capital securities;
       and

     - each trust agreement provides that the ONB Trust will not engage in any
       activity that is not consistent with the limited purposes of the ONB
       Trust.

     Old National has the right to set-off any payment Old National is otherwise
required to make under the indenture if and to the extent Old National has
already made, or is concurrently making, a payment under the related guarantee
agreement.

ENFORCEMENT RIGHTS OF HOLDERS OF CAPITAL SECURITIES

     A holder of any capital security may institute a legal proceeding directly
against Old National to enforce its rights under the related guarantee agreement
without first instituting a legal proceeding against the guarantee trustee, the
related ONB Trust or anyone else.
                                       31
<PAGE>   56

     Old National's default or event of default under any other senior or
subordinated indebtedness would not necessarily constitute a trust event of
default. However, in the event of payment defaults under, or acceleration of,
Old National's Senior Debt, the subordination provisions of the applicable
securities resolution will provide that no payments may be made in respect of
the corresponding junior subordinated debentures until the Senior Debt has been
paid in full or any payment default thereunder has been cured or waived. Old
National's failure to make required payments on any series of corresponding
junior subordinated debentures would constitute a trust event of default.

LIMITED PURPOSE OF ONB TRUSTS

     Each ONB Trust's capital securities evidence undivided beneficial ownership
interests in the assets of that ONB Trust, and each ONB Trust exists for the
sole purposes of issuing its capital securities and common securities, investing
the proceeds in junior subordinated debentures and engaging in only those other
activities necessary, convenient or incidental to those purposes. A principal
difference between the rights of a holder of a capital security and a holder of
a corresponding junior subordinated debenture is that the holder of a junior
subordinated debenture is entitled to receive from Old National the principal
amount of and interest accrued on the junior subordinated debenture held, while
the holder of a capital security is entitled to receive distributions from the
ONB Trust (or from Old National under the applicable guarantee agreement) if and
to the extent the ONB Trust has funds available for the payment of the
distributions.

RIGHTS UPON TERMINATION

     Upon any voluntary or involuntary termination of any ONB Trust involving
the liquidation of the junior subordinated debentures held by that ONB Trust,
the holders of the related capital securities will be entitled to receive the
liquidation distribution in cash, out of assets of the ONB Trust (and after
satisfaction of creditors of the ONB Trust as provided by applicable law). See
"Description of Capital Securities -- Liquidation Distribution upon
Termination." If Old National becomes subject to any voluntary or involuntary
liquidation or bankruptcy, the property trustee, as holder of the corresponding
junior subordinated debentures, would be one of Old National's junior
subordinated creditors. The property trustee would be subordinated in right of
payment to all of Old National's Senior Debt, but it would be entitled to
receive payment in full of principal and interest before Old National's
stockholders receive payments or distributions. Old National is the guarantor
under each guarantee agreement and pursuant to the indenture, as borrower, has
agreed to pay all costs, expenses and liabilities of each ONB Trust (other than
the ONB Trust's obligations to the holders of its capital securities).
Accordingly, in the event of Old National's liquidation or bankruptcy, the
positions of a holder of capital securities and of a holder of corresponding
junior subordinated debentures are expected to be substantially the same
relative to Old National's other creditors and to Old National's stockholders.

                              BOOK-ENTRY ISSUANCE

"STREET NAME" AND OTHER INDIRECT HOLDERS

     Investors who hold capital securities in accounts at banks or brokers will
generally not be recognized as legal holders of capital securities. This is
called holding in "Street Name." Instead, the applicable ONB Trust would
recognize only the bank or broker that directly holds, or the financial
institution the bank or broker uses to hold, its capital securities. These
intermediary banks, brokers and other financial institutions pass along
distributions and other payments on the capital securities, either because they
agree to do so in their customer agreements or because they are legally required
to. If you hold capital securities in "Street Name," you should check with your
own institution to find out:

     - how it handles securities payments and notices,

     - whether it imposes fees or charges,

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<PAGE>   57

     - how it would handle voting if ever required,

     - whether and how you can instruct it to send you capital securities
       registered in your own name so you can be a direct holder as described
       below, and

     - how it would pursue rights under the capital securities if there were a
       default or other event triggering the need for holders to act to protect
       their interests.

DIRECT HOLDERS

     An ONB Trust's obligations, as well as the obligations of Old National, the
trustees and those of any third parties employed by an ONB Trust, or the issuer
trustees, run only to individuals, corporations or other entities who are
registered as holders of capital securities. As noted above, an ONB Trust does
not have obligations to a holder of capital securities who holds in "Street
Name" or other indirect means, either because the holder chooses to hold capital
securities in that manner or because the capital securities are issued in the
form of global securities as described below. For example, once an ONB Trust
makes payment to the registered holder, the ONB Trust has no further
responsibility for the payment even if that holder is legally required to pass
the payment along to a holder as a "Street Name" customer but does not do so.

GLOBAL SECURITIES

     The capital securities will be issued in the form of global securities,
and, therefore, the ultimate beneficial owners can only be indirect holders. The
global securities will be registered in the name of DTC or its nominee and the
capital securities included in the global security may not be transferred in the
name of any other direct holder unless the special circumstances described below
occur. Any person wishing to own capital securities must do so indirectly by
virtue of an account with a broker, bank or other financial institution that in
turn has an account with DTC.

     Special Investor Considerations for Global Securities. As an indirect
holder, an investor's rights relating to a global security will be governed by
the account rules of the investor's financial institution and of DTC, as well as
the general laws relating to securities transfers. An investor should be aware
that because the capital securities are issued only in the form of global
securities:

     - the investor will not be able to get the capital securities registered in
       his or her own name,

     - the investor will not be able to receive physical certificates for his or
       her interest in the capital securities,

     - the investor will be a "Street Name" holder and must look to his or her
       own bank or broker for payments on the capital securities and protection
       of his or her legal rights relating to the capital securities (see
       "-- 'Street Name' and Other Indirect Holders" above),

     - the investor may not be able to sell interests in the capital securities
       to some insurance companies and other institutions that are required by
       law to own their securities in the form of physical certificates,

     - DTC's policies will govern payments, transfers, exchange and other
       matters relating to the investor's interest in the global security (see
       "-- The DTC System" below; Old National, the ONB Trusts and the issuer
       trustees have no responsibility for any aspect of DTC's actions or for
       its records of ownership interests in the global security, nor do they
       supervise DTC in any way), and

     - payment for purchases and sales in the market for corporate bonds and
       notes is generally made in next-day funds. In contrast, DTC will usually
       require that interests in a global security be purchased or sold within
       its system using same-day funds. This difference could have some effect
       on how global security interests trade, but neither Old National nor any
       ONB Trust knows what the effect will be.

                                       33
<PAGE>   58

     Special Situations When Global Security Will Be Terminated. In a few
special situations, the global security will terminate and interests in it will
be exchanged for physical certificates representing capital securities. After
the exchange, the choice of whether to hold capital securities directly or in
"Street Name" will be up to the investor. Investors must consult their own bank
or brokers to find out how to have their interests in capital securities
transferred to their own name, so that they will be direct holders. The rights
of "Street Name" investors and direct holders in the capital securities are
described above under "-- 'Street Name' and Other Indirect Holders" and
"-- Direct Holders."

     The special situations for termination of a global security are:

     - DTC notifies Old National or an ONB Trust that it is unwilling, unable or
       no longer qualified to continue as the depositary for the capital
       securities;

     - Old National in its sole discretion determines that the global security
       will be exchangeable for certificated capital securities; or

     - an event of default under the trust agreement has occurred and has not
       been cured and the holders of a majority in liquidation amount of the
       outstanding capital securities determine that the global security will be
       exchangeable for certificated capital securities.

     When a global security terminates, DTC (and not Old National or the issuer
trustees) is responsible for deciding the names of the institutions that will be
the initial direct holders.

THE DTC SYSTEM

     DTC has advised Old National that it is a limited-purpose trust company
created to hold securities for its participating organizations (the
"Participations"). DTC also facilitates the clearance and settlement between
Participants in transactions of securities deposited with DTC through changes in
the account records of its Participants. The Participants include securities
brokers and dealers, banks, trust companies, clearing corporations and certain
other organizations. The Underwriters are Participants in the DTC System. Access
to DTC's system is also available to other entities such as securities brokers
and dealers, banks and trust companies that work through a Participant (the
"Indirect Participants").

     When you purchase capital securities through the DTC system, the purchases
must be made by or through a Participant, who will receive credit for the
capital securities on DTC's records. Since you actually own the capital
securities, you are the beneficial owner and your ownership interest will only
be recorded on the Participants' or Indirect Participants' records. DTC has no
knowledge of your individual ownership of the capital securities. DTC's records
only show the identity of the Participants and the amount of the capital
securities held by or through them. You will not receive a written confirmation
of your purchase or sale or any periodic statement directly from DTC. You will
receive these from your Participant or Indirect Participant. Thus the
Participants or Indirect Participants are responsible for keeping accurate
account of the holdings of their customers like you.

     Any redemption notices will be sent by Old National and the applicable ONB
Trust directly to DTC, who will in turn inform the Participants, who will then
contact you as a beneficial holder. If less than all of the capital securities
are being redeemed, DTC's current practice is to choose by lot the amount of the
interest of each Participant to be redeemed. The Participant will then use an
appropriate method to allocate the redemption price among its beneficial holders
like you.

     It is DTC's current practice, upon receipt of any payment of distributions
or liquidation amount, to credit Participants' accounts on the payment date
based on their holdings of beneficial interests in the global securities as
shown on DTC's records. In addition, it is DTC's current practice to assign any
consenting or voting rights to Participants whose accounts are credited with
capital securities on a record date by using an omnibus proxy. Payments by
Participants to owners of beneficial interests in the global securities, and
voting by Participants, will be based on the customary practices between the
Participants and owners of beneficial interests, as is the case with the capital
securities held for the account of

                                       34
<PAGE>   59

customers registered in "Street Name." However, payments will be the
responsibility of the Participants and not of DTC, the issuer trustees, the ONB
Trusts or Old National.

     Old National has obtained the information concerning DTC and DTC's
book-entry system from sources that Old National believes to be accurate, but
Old National is not responsible for the accuracy of this information. In
addition, Old National is not responsible for the performance by DTC, its
Participants or any Indirect Participants of any of their obligations.

REGISTRATION OF JUNIOR SUBORDINATED DEBENTURES

     The junior subordinated debentures initially will be issued in certificated
form and registered in the name of the property trustee. If in the future the
junior subordinated debentures are distributed to the holders of capital
securities in exchange for the capital securities and at that time the capital
securities are represented by a global security, the junior subordinated
debentures would also be represented by a global security. In this event, Old
National expects that the book-entry arrangements applicable to the capital
securities would be similar to those applicable to the junior subordinated
debentures.

                                  UNDERWRITING

     The distribution of the securities may be effected from time to time in one
or more transactions, including negotiated transactions, at a fixed public
offering price or at varying prices determined at the time of sale. Each
prospectus supplement will describe the method of distribution of the debt
securities offered therein.

     Old National or an ONB Trust may sell the securities in any one or more of
the following ways from time to time:

     - to or through underwriters or dealers;

     - directly to one or more purchasers; or

     - through agents otherwise indicated in the prospectus supplement acting on
       a best efforts basis for the period of its appointment.

     Each prospectus supplement will set forth the terms of the offering of the
securities being offered thereby, including the name or names of any
underwriters or agents with whom Old National or an ONB Trust has entered into
arrangements for the sale of the securities, the public offering or purchase
price of those securities, the proceeds to Old National or an ONB Trust from
such sale, any underwriting discounts and other items constituting underwriters'
compensation, any discounts or concessions allowed or reallowed or paid to
dealers, any commissions allowed or paid to agents, and the name of any
securities exchange on which those securities may be listed. Only underwriters
so named in the applicable prospectus supplement are deemed to be underwriters
in connection with the securities offered thereby.

     The obligations of the underwriters to purchase those securities will be
subject to certain conditions precedent, and the underwriters will be obligated
to purchase all the securities of the series offered by any of us and described
in the applicable prospectus supplement if they purchase any of those
securities. Any initial public offering price and any discounts or concessions
allowed or reallowed or paid to dealers may be changed from time to time.

     Securities may also be offered and sold, if so indicated in the prospectus
supplement, in connection with a remarketing upon their purchase, in accordance
with a redemption or repayment pursuant to their terms, by one or more firms
("remarketing firms") acting as principals for their own accounts or as agents
for either of us. Any remarketing firm will be identified and the terms of its
agreement, if any, with us and its compensation will be described in the
prospectus supplement. Remarketing firms may be deemed to be underwriters in
connection with the securities remarketed thereby.

                                       35
<PAGE>   60

     If so indicated in the prospectus supplement, Old National or an ONB Trust
will authorize agents, underwriters or dealers to solicit offers by certain
institutions to purchase securities pursuant to delayed delivery contracts
providing for payment and delivery on a future date. There may be limitations on
the minimum amount which may be purchased by any such institutions or on the
amount of the securities which may be sold pursuant to such contracts.
Institutions with which such contracts may be made include:

     - commercial and savings banks,

     - insurance companies,

     - pension funds,

     - investment companies and

     - educational and charitable institutions.

     In each case, such institutions must be approved by Old National and/or an
ONB Trust. The obligations of any such purchasers pursuant to such delayed
delivery contracts will not be subject to any conditions except (a) the purchase
by an institution of the particular securities shall not at the time of delivery
be prohibited under the laws of any jurisdiction in the United States to which
such institution is subject, and (b) if the particular securities are being sold
to underwriters, we shall have sold to such underwriters all of those securities
other than the securities covered by such arrangements. Underwriters will not
have any responsibility in respect of the validity or performance of such
contracts.

     If any underwriter or any selling group member intends to engage in
stabilizing, syndicate short covering transactions, penalty bids or any other
transaction in connection with the offering of securities that may stabilize,
maintain, or otherwise affect the price of those securities, such intention and
a description of such transactions will be described in the prospectus
supplement.

     Agents and underwriters may be entitled under agreements entered into with
Old National and/or the applicable ONB Trust to indemnification by Old National
against certain civil liabilities, including liabilities under the Securities
Act of 1933, or to contribution with respect to payments which the agents or
underwriters may be required to make in respect thereof. Certain of any such
agents and underwriters, including their associates, may be customers of, engage
in transactions with, or perform services for, Old National and its subsidiaries
in the ordinary course of business.

                             CERTAIN LEGAL MATTERS

     Unless otherwise indicated in the applicable prospectus supplements,
certain legal matters in connection with the securities will be passed upon (a)
for Old National by Krieg DeVault Alexander & Capehart, LLP, Old National's
legal counsel, (b) for the ONB Trusts (with respect to the validity of the
capital securities under Delaware law) by Richards, Layton & Finger, P.A.,
Wilmington, Delaware, special Delaware counsel to Old National and the ONB
Trusts, and (c) for any underwriters by Cleary, Gottlieb, Steen & Hamilton,
Washington, D.C.

                                       36
<PAGE>   61

                                    EXPERTS

     The consolidated financial statements of Old National as of December 31,
1998 and December 31, 1997 and for each of the years ended December 31, 1998,
1997 and 1996 incorporated in this prospectus by reference to Old National's
Annual Report on Form 8-K filed on December 1, 1999, have been so incorporated
in reliance on the report of Arthur Andersen LLP, independent accountants, given
on the authority of that firm as experts in auditing and accounting.

     Future audited financial statements incorporated in this prospectus by
reference to future filings under the Exchange Act, as provided under "Where You
Can Find More Information," will be so incorporated in reliance on the related
report or reports of the firm of independent accountants auditing such financial
statements, given on such authority of such firm, if and to the extent such
filings include the consent of such firm to the incorporation of such report or
reports herein.

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<PAGE>   62

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                            2,000,000 PREFERRED SECURITIES (TRUPS(R))

                              ONB CAPITAL TRUST I
                  9.500% TRUST PREFERRED SECURITIES (TRUPS(R))

                     FULLY, IRREVOCABLY AND UNCONDITIONALLY
                                 GUARANTEED BY

                              OLD NATIONAL BANCORP

                           -------------------------
                             PROSPECTUS SUPPLEMENT

                                 March 9, 2000

                 (Including prospectus dated February 29, 2000)
                           -------------------------

SALOMON SMITH BARNEY
           MERRILL LYNCH & CO.
                       PAINEWEBBER INCORPORATED
                                  PRUDENTIAL SECURITIES
                                            STIFEL, NICOLAUS & COMPANY
                                                        INCORPORATED
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