VANGUARD CONVERTIBLE SECURITIES FUND INC
485BPOS, 1998-03-06
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                      SECURITIES AND EXCHANGE COMMISSION
 
                            WASHINGTON, D.C. 20549
 
                                   FORM N-1A
 
                  REGISTRATION STATEMENT (NO. 33-4424) UNDER
                          THE SECURITIES ACT OF 1933
 
                         PRE-EFFECTIVE AMENDMENT NO.                      [X]
                                                                          [X]
                     POST-EFFECTIVE AMENDMENT NO. 17     
                                      AND
 
        REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940
 
                                                                          [X]
                             AMENDMENT NO. 20     
 
                   VANGUARD CONVERTIBLESECURITIES FUND, INC.
              (EXACT NAME OF REGISTRANT AS SPECIFIED IN CHARTER)
                                 
                              P.O. BOX 2600     
                            VALLEY FORGE, PA 19482
                    (ADDRESS OF PRINCIPAL EXECUTIVE OFFICE)
 
                 REGISTRANT'S TELEPHONE NUMBER (610) 669-1000
 
                         RAYMOND J. KLAPINSKY, ESQUIRE
                                 P.O. BOX 876
                            VALLEY FORGE, PA 19482
   
  We request that this filing become effective on March 20, 1998, pursuant to
paragraph (b) of Rule 485.     
 
  Approximate Date of Proposed Public Offering: As soon as practicable after
this Registration Statement becomes effective.
   
  We have elected to register an indefinite number of shares pursuant to
Regulation 24f-2 under the Investment Company Act of 1940. We filed our Rule
24f-2 Notice for the period ended November 30, 1997 on February 27, 1998.     
 
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<PAGE>
 
                   VANGUARD CONVERTIBLE SECURITIES FUND, INC.
 
                             CROSS REFERENCE SHEET
 
<TABLE>   
<CAPTION>
  FORM N-1A
 ITEM NUMBER                                        LOCATION IN PROSPECTUS
 <C>         <C>                                    <S>
  Item 1.    Cover Page............................ Cover Page
  Item 2.    Synopsis.............................. Not Applicable
  Item 3.    Condensed Financial Information....... Financial Highlights
  Item 4.    General Description of Registrant..... Investment Objective;
                                                    Investment Limitations;
                                                    Investment Policies;
                                                    General Information
  Item 5.    Management of the Fund................ Management of the Fund;
                                                    Investment Adviser; General
                                                    Information
  Item 5A.   Management's Discussion of Fund
             Performance........................... Herein incorporated by
                                                    reference to Registrant's
                                                    Annual Report to
                                                    Shareholders dated November
                                                    30, 1997 filed with the
                                                    Securities & Exchange
                                                    Commission's EDGAR system
                                                    on January 26, 1998
  Item 6.    Capital Stock and Other Securities.... Opening an Account and
                                                    Purchasing Shares; Selling
                                                    Your Shares; The Share
                                                    Price of the Fund;
                                                    Dividends, Capital Gains
                                                    and Taxes; General
                                                    Information
  Item 7.    Purchase of Securities Being Offered.. Cover Page; Opening an
                                                    Account and Purchasing
                                                    Shares
  Item 8.    Redemption or Repurchase.............. Selling Your Shares
  Item 9.    Pending Legal Proceedings............. Not Applicable
<CAPTION>
  FORM N-1A                                         LOCATION IN STATEMENT
 ITEM NUMBER                                        OF ADDITIONAL INFORMATION
 <C>         <C>                                    <S>
  Item 10.   Cover Page............................ Cover Page
  Item 11.   Table of Contents..................... Cover Page
  Item 12.   General Information and History....... Investment Advisory
                                                    Services; General
                                                    Information
  Item 13.   Investment Objective and Policies..... General Information;
                                                    Investment Limitations
  Item 14.   Management of the Registrant.......... Management of the Fund;
                                                    Investment Advisory
                                                    Services
  Item 15.   Control Persons and Principal Holders
             of Securities......................... Management of the Fund;
                                                    General Information
  Item 16.   Investment Advisory and Other          Management of the Fund;
             Services.............................. Investment Advisory
                                                    Services
  Item 17.   Brokerage Allocation.................. Not Applicable
  Item 18.   Capital Stock and Other Securities.... General Information;
                                                    Financial Statements
  Item 19.   Purchase, Redemption and Pricing of
             Securities Being Offered.............. Purchase of Shares;
                                                    Redemption of Shares
  Item 20.   Tax Status............................ Not Applicable
  Item 21.   Underwriters.......................... Not Applicable
  Item 22.   Calculations of Performance Data...... Not Applicable
  Item 23.   Financial Statements.................. Financial Statements
</TABLE>    
<PAGE>
 
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                                                 A Member of The Vanguard Group
[LOGO OF VANGUARD APPEARS HERE]
 
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PROSPECTUS--MARCH 20, 1998     
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NEW ACCOUNT INFORMATION: INVESTOR INFORMATION DEPARTMENT--1-800-662-7447 (SHIP)
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SHAREHOLDER ACCOUNT SERVICES: CLIENT SERVICES DEPARTMENT--1-800-662-2739 (CREW)
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INVESTMENT         Vanguard Convertible Securities Fund, Inc. (the "Fund") is
OBJECTIVE AND      an open-end diversified investment company that seeks to
POLICIES           provide current income and long-term growth of capital.
                   The Fund invests primarily in corporate bonds and pre-
                   ferred stocks that are convertible into shares of common
                   stock. Although the Fund is designed principally for equi-
                   ty-oriented investors, you should be aware that a majority
                   of the Fund's assets may be invested in convertible secu-
                   rities rated Ba or B by Moody's Investors Service or BB or
                   B by Standard & Poor's Corporation. Corporate bonds with
                   such ratings are commonly referred to as "junk bonds" and
                   are considered speculative by the major ratings agencies.
                   There is no assurance that the Fund will achieve its
                   stated objectives. Shares of the Fund are neither insured
                   nor guaranteed by any agency of the U.S. Government, in-
                   cluding the FDIC.
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OPENING AN         To open a regular (non-retirement) account, please com-
ACCOUNT            plete and return the Account Registration Form. If you
                   need assistance in completing this Form, please call the
                   Investor Information Department. To open an Individual Re-
                   tirement Account (IRA), please use a Vanguard IRA Adoption
                   Agreement. To obtain a copy of this form, call 1-800-662-
                   7447, Monday through Friday, from 8:00 a.m. to 9:00 p.m.
                   and Saturday from 9:00 a.m. to 4:00 p.m. (Eastern time).
                   The minimum initial investment is $3,000, or $1,000 for
                   Individual Retirement Accounts and Uniform Gifts/Transfers
                   to Minors Act accounts. The Fund is offered on a no-load
                   basis (i.e., there are no sales commissions or 12b-1
                   fees). However, the Fund incurs expenses for investment
                   advisory, management, administrative and distribution
                   services.     
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ABOUT THIS         This Prospectus is designed to set forth concisely the in-
PROSPECTUS         formation you should know about the Fund before you in-
                   vest. It should be retained for future reference. A
                   "Statement of Additional Information" containing addi-
                   tional information about the Fund has been filed with the
                   Securities and Exchange Commission. This Statement is
                   dated March 20, 1998, and has been incorporated by refer-
                   ence into this Prospectus. It may be obtained without
                   charge by writing to the Fund, calling the Investor Infor-
                   mation Department at 1-800-662-7447, or visiting the Secu-
                   rities and Exchange Commission's website (www.sec.gov).
                       
<TABLE>     
<CAPTION> 
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TABLE OF CONTENTS
                                   Page
<S>                                <C> 
Fund Expenses....................    2
Financial Highlights.............    2
Yield and Total Return...........    3

      FUND INFORMATION

Investment Objective.............    4
Investment Policies..............    4
Investment Risks.................    5
Who Should Invest................    6
Implementation of Policies.......    7
Investment Limitations...........    9

                                   Page
Management of the Fund...........    9
Investment Adviser...............   10
Performance Record...............   12
Dividends, Capital Gains and 
  Taxes..........................   12
The Share Price of the Fund......   14
General Information..............   14

     SHAREHOLDER GUIDE

Opening an Account and
 Purchasing Shares...............   16


                                   Page
When Your Account Will Be 
  Credited.......................   19
Selling Your Shares..............   20
Exchanging Your Shares...........   22
Important Information About 
  Telephone Transactions.........   24
Transferring Registration........   24
Other Vanguard Services..........   25
</TABLE>      
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THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION, NOR HAS THE SECURITIES AND EXCHANGE COMMISSION PASSED
UPON THE ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE
CONTRARY IS A CRIMINAL OFFENSE.     
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<PAGE>
 
    
FUND EXPENSES   The following table illustrates ALL expenses and fees that you
                would incur as a shareholder of the Fund. The expenses set forth
                below are for the 1997 fiscal year.     
 
<TABLE>   
<CAPTION>
                SHAREHOLDER TRANSACTION EXPENSES
                ---------------------------------------------------------------
                <S>                                                       <C>
                Sales Load Imposed on Purchases.........................  None
                Sales Load Imposed on Reinvested Dividends..............  None
                Redemption Fees.........................................  None
                Exchange Fees...........................................  None
<CAPTION>
                ANNUAL FUND OPERATING EXPENSES
                ---------------------------------------------------------------
                <S>                                                   <C> <C>
                Management & Administrative Expenses....................  0.24%
                Investment Advisory Fees................................  0.37%
                12b-1 Fees..............................................  None
                Other Expenses
                   Distribution Costs................................ 0.02%
                   Miscellaneous Expenses............................ 0.04
                                                                      ----
                Total Other Expenses....................................  0.06
                                                                          ---
                      TOTAL OPERATING EXPENSES..........................  0.67%
                                                                          ====
</TABLE>    
 
                The purpose of this table is to assist you in understand-ing the
                various costs and expenses that you would bear di-rectly or
                indirectly as an investor in the Fund.
 
                The following example illustrates the expenses that you would
                incur on a $1,000 investment over various periods, assuming (1)
                a 5% annual rate of return and (2) redemption at the end of each
                period. As noted in the table above, the Fund charges no
                redemption fees of any kind.
 
<TABLE>   
<CAPTION>
                  1 YEAR          3 YEARS            5 YEARS          10 YEARS
                  ------          -------            -------          --------
                  <S>             <C>                <C>              <C>
                    $7              $21                $37              $83
</TABLE>    
 
                   THIS EXAMPLE SHOULD NOT BE CONSIDERED A REPRESENTATION OF
                   PAST OR FUTURE EXPENSES OR PERFORMANCE. ACTUAL EXPENSES
                   MAY BE HIGHER OR LOWER THAN THOSE SHOWN.
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FINANCIAL          The following financial highlights for a share outstanding
HIGHLIGHTS         throughout each period, insofar as they relate to each of
                   the five years in the period ended November 30, 1997, have
                   been derived from financial statements which were audited
                   by Price Waterhouse LLP, independent accountants, whose
                   report thereon was unqualified. This information should be
                   read in conjunction with the Fund's financial statements
                   and notes thereto, which, together with the remaining por-
                   tions of the Fund's 1997 Annual Report to Shareholders,
                   are incorporated by reference in the Statement of Addi-
                   tional Information and in this Prospectus, and which ap-
                   pear, along with the report of Price Waterhouse LLP, in
                   the Fund's 1997 Annual Report to Shareholders. For a more
                   complete discussion of the Fund's performance, please see
                   the Fund's 1997 Annual Report to Shareholders, which may
                   be obtained without charge by writing to the Fund or by
                   calling our Investor Information Department at 1-800-662-
                   7447.     
 
2
<PAGE>
 
<TABLE>   
<CAPTION>
                                                YEAR ENDED NOVEMBER 30,
                          ----------------------------------------------------------------------------
                            1997    1996    1995    1994    1993    1992   1991     1990   1989   1988
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<S>                       <C>     <C>     <C>     <C>     <C>     <C>     <C>    <C>      <C>    <C>
NET ASSET VALUE,
 BEGINNING
 OF YEAR................  $13.07  $12.03  $10.94  $12.89  $11.77  $ 9.82  $8.07    $9.64  $8.71  $7.94
                          ------  ------  ------  ------  ------  ------  -----  -------  -----  -----
INVESTMENT OPERATIONS
 Net Investment Income..     .53     .43     .52     .53     .56     .56    .53      .57    .51    .55
 Net Realized and
  Unrealized Gain (Loss)
  on Investments........    1.17    1.29    1.26   (1.04)   1.03    1.92   1.77    (1.58)   .99    .90
                          ------  ------  ------  ------  ------  ------  -----  -------  -----  -----
  TOTAL FROM INVESTMENT
   OPERATIONS...........    1.70    1.72    1.78    (.51)   1.59    2.48   2.30    (1.01)  1.50   1.45
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DISTRIBUTIONS
 Dividends from Net
  Investment Income.....    (.47)   (.54)   (.51)   (.53)   (.47)   (.53)  (.55)    (.56)  (.57)  (.56)
 Distributions from
  Realized
  Capital Gains.........   (1.29)   (.14)   (.18)   (.91)    --      --     --       --     --    (.12)
                          ------  ------  ------  ------  ------  ------  -----  -------  -----  -----
  TOTAL DISTRIBUTIONS...   (1.76)   (.68)   (.69)  (1.44)   (.47)   (.53)  (.55)    (.56)  (.57)  (.68)
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NET ASSET VALUE, END OF
 PERIOD.................  $13.01  $13.07  $12.03  $10.94  $12.89  $11.77  $9.82    $8.07  $9.64  $8.71
=======================================================================================================
TOTAL RETURN............   14.81%  14.88%  17.10% (4.35)%  13.87%  26.01% 29.25% (10.95)% 17.70% 18.85%
RATIOS/SUPPLEMENTAL DATA
=======================================================================================================
Net Assets, End of Year
 (Millions).............  $  189  $  170  $  172  $  175  $  202  $  120  $  55  $    44  $  58  $  69
Ratio of Total Expenses
 to Average
 Net Assets.............    0.67%   0.69%   0.75%   0.73%   0.71%   0.85%  0.81%    0.88%  0.84%  0.88%
Ratio of Net Investment
 Income to Average Net
 Assets.................    4.29%   3.43%   4.63%   4.68%   4.44%   4.80%  5.72%    6.35%  5.60%  6.52%
Portfolio Turnover Rate.     182%     97%     46%     52%     81%     55%    57%      55%    55%    24%
Average Commission Rate
 Paid...................  $.0593  $.0594     N/A     N/A     N/A     N/A    N/A      N/A    N/A    N/A
</TABLE>    
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YIELD AND TOTAL    From time to time the Fund may advertise its yield and to-
RETURN             tal return. Both yield and total return figures are based
                   on historical earnings and are not intended to indicate
                   future performance. The "total return" of the Fund refers
                   to the average annual compounded rates of return over one-,
                   five- and ten-year periods or the life of the Fund (as stated
                   in the advertisement) that would equate an initial amount
                   invested at the beginning of a stated period to the ending
                   redeemable value of the investment, assuming the reinvestment
                   of all dividend and capital gains distribu-tions.
 
                   In accordance with industry guidelines set forth by the
                   U.S. Securities and Exchange Commission, the "30-day
                   yield" of the Fund is calculated by dividing the net in-
                   vestment income per share earned during a 30-day period by
                   the net asset value per share on the last day of the peri-
                   od. Net investment income includes interest and dividend
                   income earned on the Fund's securities; it is net of all
                   expenses and all recurring and nonrecurring charges that
                   have been applied to all shareholder accounts. The yield
                   calculation assumes that the net investment income earned
                   over 30 days is compounded monthly for six months and then
                   annualized. Methods used to calculate advertised yields
                   are standardized for all stock and bond mutual funds. How-
                   ever, these methods differ from the accounting methods
                   used by the Fund to maintain its books and records, and so
                   the advertised 30-day yield may not fully reflect the in-
                   come paid to an investor's account or the yield reported
                   in the Fund's reports to shareholders.
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                                                                              3
<PAGE>
 
INVESTMENT         Vanguard Convertible Securities Fund, Inc. (the "Fund") is
OBJECTIVE          an open-end diversified investment company. The objective
                   of the Fund is to provide current income and long-term
THE FUND SEEKS     growth of capital by investing primarily in convertible
TO PROVIDE         securities. There is no assurance that the Fund will
CURRENT INCOME     achieve its objective.
AND LONG-TERM 
GROWTH             The investment objective of the Fund is fundamental and so
                   cannot be changed without the approval of a majority of  
                   the Fund's shareholders.                                  
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INVESTMENT         Under normal circumstances, at least 80% of the Fund's as-
POLICIES           sets will be invested in convertible securities. Convert-
                   ible securities include corporate bonds and preferred
THE FUND INVESTS   stocks which are convertible into common stock, as well as
IN CONVERTIBLE     debt instruments with warrants or common stock attached.
SECURITIES         See "Implementation of Policies" for a description of con-
                   vertible securities.
 
                   The remaining 20% of the Fund's assets may be invested in
                   non-convertible corporate or U.S. Government fixed-income
                   securities, common stocks, and selected money market in-
                   struments. Within this 20% limit, the Fund is authorized
                   to write covered call options on its investments, although
                   it does not presently intend to do so. The Fund may also
                   invest more than 20% of its assets in money market instru-
                   ments when the Fund's investment adviser determines that a
                   temporary defensive position is warranted.
                      
                   In seeking to provide both current income and long-term
                   capital appreciation, the adviser will emphasize the secu-
                   rities of companies with above-average growth potential
                   whose convertible securities offer attractive yields. In
                   general, each security selected for the Fund will, in the
                   opinion of the adviser, be priced at a reasonable premium
                   relative to the price at which it can be converted into
                   common stock.     
 
                   The Fund will predominantly invest in convertible obliga-
                   tions which have been assigned a rating of B or better by
                   Moody's Investors Service, Inc. ("Moody's") or Standard &
                   Poor's Corporation ("Standard & Poor's"). The Fund may
                   also invest in non-rated securities that, in the opinion
                   of the Fund's adviser, are equivalent in quality to a B
                   rating or better.
 
                   While the Fund will invest predominately in securities of
                   U.S.-based companies, up to 20% of the Fund's assets may
                   be invested in dollar-denominated securities issued by
                   foreign companies. See "Implementation of Policies" for a
                   description of other investment practices of the Fund.
 
                   The Fund is responsible for voting the shares of all secu-
                   rities it holds.
                      
                   These policies are not fundamental and so may be changed
                   by the Board of Directors without shareholder approval.
                   However, before making any important change in its poli-
                   cies, the Fund will give shareholders 30-days notice, in
                   writing.     
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4
<PAGE>
 
INVESTMENT RISKS   Convertible securities are hybrid securities, combining
                   the investment characteristics of both bonds and common
THE FUND IS        stocks. Like a bond (or preferred stock), a convertible
SUBJECT TO STOCK   security pays a fixed interest rate (dividend), but may be
AND BOND MARKET    converted into common stock at a specific price or conver-
RISK               sion rate.
 
                   When the convertible's conversion price is significantly
                   above the price of the issuer's common stock, a convert-
                   ible security takes on the risk characteristics of a bond.
                   At such times, the price of a convertible security will
                   vary inversely with changes in the level of interest
                   rates. In other words, when interest rates rise, convert-
                   ible securities prices will generally fall; conversely,
                   when interest rates fall, convertible securities prices
                   will generally rise. This interest rate risk is in part
                   offset by the income paid by the convertible securities.
 
                   In contrast, when the conversion price of a convertible
                   security and the common stock price are close to one an-
                   other, a convertible security will behave like a common
                   stock. In such cases, the prices of convertible securities
                   may exhibit the short-term price volatility characteristic
                   of common stocks.
 
                   For these reasons, investors in the Fund must be willing
                   to accept the market risks of both bonds and stocks. How-
                   ever, because convertible securities have characteristics
                   of both stocks and bonds, they tend to be less sensitive
                   to interest rate changes than bonds of comparable maturity
                   and quality, and less sensitive to stock market changes
                   than fully invested common stock portfolios. Because of
                   these factors and the hybrid nature of convertibles, in-
                   vestors should recognize that convertible securities are
                   likely to perform quite differently than broadly-based
                   measures of the stock and bond markets.
                   
INTERNATIONAL      The Fund may invest as much as 20% of its assets in for-
STOCKS EXPOSE      eign securities. These securities can be traded in either
INVESTORS TO       U.S. or foreign markets. Because of its foreign invest-
COUNTRY RISKS      ments, the Fund is subject to country risk and currency
AND CURRENCY       risk. Country risk is the possibility that political
RISKS              events (such as a war), financial problems (such as gov-
                   ernment default), or natural disasters (such as an earth-
                   quake) will weaken a country's economy and cause invest-
                   ments in that country to lose money. Currency risk is the
                   possibility that a "stronger" U.S. dollar will reduce re-
                   turns for Americans investing overseas. Generally, when
                   the dollar rises in value against a foreign currency, your
                   investment in that country loses value because its cur-
                   rency is worth fewer U.S. dollars.     
              
CREDIT QUALITY     The market for convertible securities includes a larger
MAY BE LOW         proportion of small-to-medium size companies than the
                   broad stock market (as measured by such indices as the
                   Standard & Poor's 500 Composite Stock Price Index). Compa-
                   nies which issue convertible securities are often lower in
                   credit quality. Moreover, the credit rating of a company's
                   convertible issue is generally lower than the rating of
                   the company's conventional debt issues since the convert-
                   ible is normally a "junior" security. The average credit
                   quality of the Fund is expected to be on a par with the
                   universe of convertible securities as a whole, and the
                   Fund may invest up to 100% of its assets in securities
                   rated Ba (BB) or less. Securities with such ratings
 
                                                                              5
<PAGE>
 
                   are considered speculative, and thus pose a greater risk
                   of default than investment grade securities. The following
                   are excerpts from the Moody's and Standard & Poor's defi-
                   nitions for speculative debt obligations:
 
                   Moody's: Ba-rated bonds have "speculative elements," their
                   future "cannot be considered assured," and protection of
                   principal and interest is "moderate" and "not well safe-
                   guarded." B-rated bonds "lack characteristics of a desir-
                   able investment" and the assurance of interest or princi-
                   pal payments "may be small."
 
                   Caa-rated bonds are "of poor standing" and "may be in de-
                   fault" or may have "elements of danger with respect to
                   principal or interest."
 
                   Standard & Poor's: BB-rated bonds have "less near-term
                   vulnerability to default" than B- or CCC-rated securities
                   but face "major ongoing uncertainties . . . which may lead
                   to inadequate capacity" to pay interest or principal. B-
                   rated bonds have a "greater vulnerability to default" than
                   BB-rated bonds and the ability to pay interest or princi-
                   pal will likely be impaired by adverse business condi-
                   tions. CCC-rated bonds have a "currently identifiable vul-
                   nerability to default" and, without favorable business
                   conditions, will be unable to repay interest and princi-
                   pal.
 
                   Securities rated Ba or lower are considered to be "high-
                   risk" securities and the credit quality of such securities
                   can change suddenly and unexpectedly, and even recently-
                   issued credit ratings may not fully reflect the actual
                   risks of a particular security. For these reasons, it is
                   the Fund's policy not to rely primarily on ratings issued
                   by established credit rating agencies, but to utilize such
                   ratings in conjunction with the Portfolio adviser's own
                   independent and ongoing review of the companies repre-
                   sented in the Fund.
                      
                   In the past, the high yields from a portfolio of low-grade
                   securities have more than compensated for the higher de-
                   fault rates on such securities. However, there can be no
                   assurance that diversification will protect the Fund from
                   widespread defaults brought about by a sustained economic
                   downturn, or that yields will continue to offset default
                   rates on high-yield securities in the future.     
                          
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WHO SHOULD         The Fund is intended for investors who are seeking a
INVEST             higher level of income than is normally available from
                   common stocks, as well as potential long-term capital ap-
INVESTORS          preciation. Since the Fund may own non-investment grade
SEEKING CURRENT    securities of medium-to-small-sized companies, greater-
INCOME AND LONG-   than-average investment risk may be involved. Investors
TERM CAPITAL       should be able to tolerate sharp, sometimes sudden fluctu-
GROWTH             ations in the value of their investment in pursuit of
                   higher investment returns in the long run.
 
                   Although convertible securities exhibit characteristics of
                   both stocks and bonds, the Fund does not represent a com-
                   plete investment program. Most investors should maintain
                   diversified holdings of securities with different risk
                   characteristics--including common stocks, bonds and money
                   market instruments. The Fund is intended to be a long-term
                   investment vehicle and is not designed to provide invest-
                   ors with a means of speculating on short-term market move-
                   ments.
 
6
<PAGE>
 
                   Investors who engage in excessive account activity gener-
                   ate additional costs which are borne by all of the Fund's
                   shareholders. In order to minimize such costs, the Fund
                   has adopted the following policies. The Fund reserves the
                   right to reject any purchase request (including exchange
                   purchases from other Vanguard portfolios) that is reasona-
                   bly deemed to be disruptive to efficient portfolio manage-
                   ment, either because of the timing of the investment or
                   previous excessive trading by the investor. Additionally,
                   the Fund has adopted exchange privilege limitations as de-
                   scribed in the section "Exchange Privilege Limitations."
                   Finally, the Fund reserves the right to suspend the offer-
                   ing of its shares.
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IMPLEMENTATION     The Fund uses a number of investment vehicles to achieve
OF POLICIES        its objective.
 
THE FUND INVESTS   The Fund invests primarily in convertible securities. Con-
IN CONVERTIBLE     vertible securities include corporate bonds, debentures,
SECURITIES         notes and preferred stocks which may be converted into the
                   common stock of the issuer at the holder's option. Con-
                   vertible securities obligate the issuing company to pay a
                   stated annual rate of interest (or a stated dividend in
                   the case of convertible preferred stock) and to return the
                   principal amount after a specified period. Convertible se-
                   curities generally offer income yields that are higher
                   than the dividend yield, if any, of the underlying common
                   stock, but lower than the yield of non-convertible debt
                   securities issued by the corporation or corporations of
                   similar investment quality. This fixed-income feature of
                   convertible securities is expected to enable the Fund to
                   achieve its current income objective. Convertible securi-
                   ties are usually priced at a premium to their conversion
                   value--i.e., the value of the common stock received if the
                   holder were to exchange the convertible security.

                   The holder of the convertible security may choose at any
                   time to exchange the convertible security for a specified
                   number of shares of the common stock of the corporation,
                   or occasionally a subsidiary company, at a specified
                   price, as defined by the corporation when the security is
                   issued. Accordingly, the value of the convertible obliga-
                   tion may generally be expected to increase (decrease) as
                   the price of the associated common stock increases (de-
                   creases). Also, the market value of convertible securities
                   tends to be influenced by the level of interest rates and
                   tends to decline as interest rates increase and, converse-
                   ly, to increase as interest rates decline.
                      
                   Convertible securities rank senior to common stocks in an
                   issuer's capital structure, but are generally junior to
                   non-convertible debt securities. As convertible securities
                   are considered junior to any non-convertible debt securi-
                   ties issued by the corporation, convertible securities are
                   typically rated by established credit rating services at
                   one level below the corporation's non-convertible debt.
                       
                
THE FUND MAY       Although it normally seeks to remain fully invested in
INVEST IN SHORT-   convertible securities, the Fund may invest in certain
TERM FIXED         short-term fixed income securities. Such securities may be
INCOME             used to invest uncommitted cash balances, to maintain li-
SECURITIES         quidity to meet shareholder redemptions, or to take a tem-
                   porary defensive position. These securities include: obli-
                   gations of the United States Government and its agencies
                   or
 
                                                                              7
<PAGE>
 
                   instrumentalities, commercial paper, bank certificates of
                   deposit, and bankers' acceptances, and repurchase agree-
                   ments collateralized by these securities.
 
THE FUND MAY       The Fund may lend its investment securities on a short-
LEND ITS           term or a long-term basis to qualified institutional in-
SECURITIES         vestors for the purpose of realizing additional income.
                   Loans of securities by the Fund will be collateralized by
                   cash, letters of credit, or securities issued or guaran-
                   teed by the U.S. Government or its agencies. The collat-
                   eral will equal at least 100% of the current market value
                   of the loaned securities.
 
THE FUND MAY       The Fund may borrow money, subject to the limits set forth
BORROW MONEY       below, for temporary or emergency purposes, including the
                   meeting of redemption requests which might otherwise re-
                   quire the untimely disposition of securities.
 
   
PORTFOLIO          The Fund retains the right to sell securities irrespective
TURNOVER IS NOT    of how long they have been held. However, depending on
EXPECTED TO        market conditions and other factors, it is expected that
EXCEED 100%        the portfolio turnover rate for the Fund will not normally
                   exceed 100%. Because of the Fund's change in investment
                   adviser in November 1996, the turnover rate for 1997 ex-
                   ceeded 100%. A turnover rate of 100% would occur, for ex-
                   ample, if all of the Fund's securities were replaced
                   within one year.     
 
DERIVATIVE         Derivatives are instruments whose values are linked to or
INVESTING          derived from an underlying security or index. The most
                   common and conventional types of derivative securities are
                   futures and options.
 
THE FUND MAY       The Fund may invest in futures contracts and options, but
INVEST IN          only to a limited extent. Specifically, the Fund may enter
DERIVATIVE         into futures contracts provided that not more than 5% of
SECURITIES         its assets are required as a futures contract deposit; in
                   addition, the Fund may enter into futures contracts and
                   options transactions only to the extent that obligations
                   under such contracts or transactions represent not more
                   than 20% of the Fund's assets.
 
                   Futures contracts and options may be used for several com-
                   mon fund management strategies: to maintain cash reserves
                   while simulating full investment, to facilitate trading,
                   to reduce transaction costs, or to seek higher investment
                   returns when a specific futures contract is priced more
                   attractively than other futures contracts or the under-
                   lying security or index.
 
                   The Fund may use futures contracts for bona fide "hedging"
                   purposes. In executing a hedge, a manager sells, for exam-
                   ple, stock index futures to protect against a decline in
                   the stock market. As such, if the market drops, the value
                   of the futures position will rise, thereby offsetting the
                   decline in value of the Fund's stock holdings.
              
FUTURES            The primary risks associated with the use of futures con-
CONTRACTS AND      tracts and options are: (i) imperfect correlation between
OPTIONS POSE       the change in market value of the stocks held by the Fund
CERTAIN RISKS      and the prices of futures contracts and options; and (ii)
                   possible lack of a liquid secondary market for a futures
                   contract and the resulting inability to close a futures
                   position prior to its maturity date. The risk of imperfect
                   correlation will be minimized by investing in those con-
                   tracts whose price fluctuations are
 
8
<PAGE>
 
                   expected to resemble those of the Fund's underlying secu-
                   rities. The risk that the Fund will be unable to close out
                   a futures position will be minimized by entering into such
                   transactions on a national exchange with an active and
                   liquid secondary market.
 
                   The risk of loss in trading futures contracts in some
                   strategies can be substantial, due both to the low margin
                   deposits required and the extremely high degree of lever-
                   age involved in futures pricing. As a result, a relatively
                   small price movement in a futures contract may result in
                   immediate and substantial loss (or gain) to the investor.
                   When investing in futures contracts, the Fund will segre-
                   gate cash or other liquid portfolio securities in the
                   amount of the underlying obligation.
- -------------------------------------------------------------------------------
   
INVESTMENT         The Fund has adopted limitations on some of its investment
LIMITATIONS        policies. Some of these limitations are that the Fund will
                   not:     
               
THE FUND HAS       (a) with respect to 75% of the value of its total assets,
ADOPTED CERTAIN        purchase the securities of any issuer (except
FUNDAMENTAL            obligations of the United States Government and its
LIMITATIONS            instrumentalities) if as a result the Fund would hold
                       more than 10% of the outstanding voting securities of
                       the issuer, or more than 5% of the value of the Fund's
                       total assets would be invested in the securities of
                       such issuer;
 
                   (b) invest more than 5% of its assets in the securities of
                       companies that have a continuous operating history of
                       less than three years;
 
                   (c) invest more than 25% of its assets in any one
                       industry;
                      
                   (d) borrow money, except that the Fund may borrow from
                       banks (or through reverse repurchase agreements), for
                       temporary or emergency (not leveraging) purposes,
                       including the meeting of redemption requests which
                       might otherwise require the untimely disposition of
                       securities, in an amount not exceeding 10% of the
                       value of the Fund's net assets (including the amount
                       borrowed) at the time the borrowing is made. Whenever
                       borrowings exceed 5% of the value of the Fund's net
                       assets, the Fund will not make any additional
                       investments;     
 
                   (e) pledge, mortgage or hypothecate any of its assets to
                       an extent greater than 5% of its total assets.
                      
                   A complete list of the Fund's investment limitations can
                   be found in the Statement of Additional Information. These
                   limitations are fundamental and may be changed only by ap-
                   proval of a majority of the Fund's shareholders.     
- -------------------------------------------------------------------------------
   
MANAGEMENT OF      The Fund is a member of The Vanguard Group of Investment
THE FUND           Companies, a family of more than 30 funds, with more than
                   95 portfolios and total assets in excess of $330 billion.
VANGUARD           Through their jointly-owned subsidiary, The Vanguard
ADMINISTERS AND    Group, Inc. ("Vanguard"), the Fund and the other funds in
DISTRIBUTES THE    the Group obtain at cost virtually all of their corporate
FUND               management, administrative, shareholder accounting and
                   distribution services. Vanguard also provides investment
                   advisory services on an at-cost basis to certain Vanguard
                   funds. As a result of Vanguard's unique     
 
                                                                              9
<PAGE>
 
                      
                   corporate structure, the Vanguard funds have costs sub-
                   stantially lower than those of most competing mutual
                   funds. In 1997, the average expense ratio (annual costs
                   including advisory fees divided by total net assets) for
                   the Vanguard funds amounted to approximately 0.28% com-
                   pared to an average of 1.24% for other mutual funds (data
                   provided by Lipper Analytical Services).     
 
                   The Officers of the Fund manage its day-to-day operations
                   and are responsible to the Fund's Board of Directors. The
                   Directors set broad policies for the Fund and choose its
                   Officers. A list of the Directors and Officers of the Fund
                   and a statement of their present positions and principal
                   occupations during the past five years can be found in the
                   Statement of Additional Information.
 
                   Vanguard employs a supporting staff of management and ad-
                   ministrative personnel needed to provide the requisite
                   services to the funds and also furnishes the funds with
                   necessary office space, furnishings and equipment. Each
                   fund pays its share of Vanguard's total expenses, which
                   are allocated among the funds under methods approved by
                   the Board of Directors (Trustees) of each fund. In addi-
                   tion, each fund bears its own direct expenses, such as le-
                   gal, auditing and custodian fees.
 
                   Vanguard also provides distribution and marketing service
                   to the Vanguard funds. The funds are available on a no-
                   load basis (i.e., there are no sales commissions or 12b-1
                   fees). However, each fund bears its share of Vanguard's
                   distribution costs.
- -------------------------------------------------------------------------------
INVESTMENT         The Fund employs Oaktree Capital Management, LLC
ADVISER            ("Oaktree"), 550 South Hope Street, 22nd Floor, Los Ange-
                   les, California, 90071, under an investment advisory
OAKTREE CAPITAL    agreement dated November 1, 1996, to manage the investment
MANAGEMENT, LLC    and reinvestment of the assets of the Fund and to continu-
MANAGES THE        ously review, supervise and administer the Fund's invest-
FUND'S             ment program. Oaktree discharges its responsibilities sub-
INVESTMENTS        ject to the control of the Officers and Directors of the
                   Fund.
 
                   Oaktree specializes in selected niche investment markets.
                   The founders of Oaktree formed the company in April of
                   1995 after having managed funds in the convertible securi-
                   ties, distressed debt, and high yield bond areas of Trust
                   Company of the West since 1985.
                      
                   Larry W. Keele, Principal and one of the five founders of
                   Oaktree, serves as Portfolio Manager of the Fund. Mr.
                   Keele is supported by research and other investment serv-
                   ices provided by the professional staff of Oaktree. As of
                   November 30, 1997, Oaktree managed approximately $9.7 bil-
                   lion.     
 
10
<PAGE>
 
                   The Fund pays Oaktree an advisory fee at the end of each
                   fiscal quarter, calculated by applying a quarterly rate,
                   based on the following annual percentage rates, to the
                   Fund's average month-end net assets for the quarter (the
                   "Basic Fee"):
 
<TABLE>
<CAPTION>
                    NET ASSETS                                           RATE
                    ------------------                                  ------
                    <S>                                                 <C>
                    First $100 million                                  0.425%
                    Next $100 million                                   0.400%
                    Next $100 million                                   0.375%
                    Next $100 million                                   0.350%
                    Over $400 million                                   0.325%
</TABLE>
 
                   The advisory fee may be increased or decreased by an
                   incentive/penalty fee based on the Fund's total return
                   performance as compared to that of the First Boston Con-
                   vertible Securities Index. Under the fee schedule, the Ba-
                   sic Fee may be increased or decreased by as much as 50%.
 
                   The incentive/penalty fee structure will not be in full
                   operation until the quarter ending November 30, 1999. Un-
                   til then, the incentive/penalty fee will be calculated us-
                   ing certain transition rules. The incentive/penalty fee
                   schedule and calculation process for the Portfolio's first
                   three years are described in the Portfolio's Statement of
                   Additional Information, which can be obtained by writing
                   to or calling Vanguard.
                      
                   During the fiscal year ended November 30, 1997, the total
                   advisory fees paid by the Fund to Oaktree represented an
                   effective annual base rate of 0.42% of the Fund's average
                   net assets before a decrease of 0.05% based on perfor-
                   mance.     
 
                   The investment advisory agreement authorizes Oaktree to
                   select the brokers or dealers that will execute the pur-
                   chases and sales of portfolio securities for the Fund and
                   directs Oaktree to use its best efforts to obtain the best
                   available price and most favorable execution with respect
                   to all transactions for the Fund. The full range and qual-
                   ity of brokerage services are considered in making
                   these determinations.
 
                   The Fund has authorized Oaktree to pay higher commissions
                   in recognition of brokerage services felt necessary for
                   the achievement of better execution, provided the adviser
                   believes this to be in the best interest of the Fund. If
                   more than one broker can obtain the best available price
                   and favorable execution of a transaction, then Oaktree is
                   authorized to choose a broker who, in addition to execut-
                   ing the transaction, will provide research services to
                   Oaktree or the Fund. However, Oaktree will not pay higher
                   commissions specifically for the purpose of obtaining re-
                   search services. The Fund may direct Oaktree to use a par-
                   ticular broker for certain transactions in exchange for
                   commission rebates or research services provided to the
                   Fund.
 
                   The Fund's Board of Directors may, without the approval of
                   shareholders, provide for: (a) the employment of a new in-
                   vestment adviser pursuant to the terms of a new advisory
                   agreement, either as a replacement for an existing adviser
                   or as an additional adviser; (b) a change in the terms of
                   an advisory agreement; and
 
                                                                             11
<PAGE>
 
                   (c) the continued employment of an existing adviser on the
                   same advisory contract terms where a contract has been as-
                   signed because of a change in control of the adviser. Any
                   such change will only be made upon not less than 30 days'
                   prior written notice to shareholders of the Fund, which
                   shall include substantially the information concerning the
                   adviser that would have normally been included in a proxy
                   statement.
- -------------------------------------------------------------------------------
PERFORMANCE        The table in this section provides investment results for
RECORD             the Fund for several periods throughout the Fund's life-
                   time. The results shown represent the Fund's "total re-
                   turn" investment performance, which assumes the reinvest-
                   ment of all capital gains and income dividends for the in-
                   dicated periods. Also included is comparative information
                   with respect to the unmanaged Standard & Poor's 500 Com-
                   posite Stock Price Index, a widely-used barometer of stock
                   market activity, and the Lehman Aggregate Bond Index, a
                   measure of the investment performance of the bond market.
                   The table does not make any allowance for federal, state
                   or local income taxes, which shareholders must pay on a
                   current basis.
 
                   The results should not be considered a representation of
                   the total return from an investment made in the Fund to-
                   day. This information is provided to help investors better
                   understand the Fund and may not provide a basis for com-
                   parison with other investments or mutual funds which use a
                   different method to calculate performance.
 
                                 AVERAGE ANNUAL TOTAL RETURN FOR
                              VANGUARD CONVERTIBLE SECURITIES FUND
 
<TABLE>   
<CAPTION>
                                                                     LEHMAN
             FISCAL PERIODS    VANGUARD CONVERTIBLE   S&P 500    AGGREGATE BOND
             ENDED 11/30/97      SECURITIES FUND       INDEX         INDEX
             --------------    --------------------   -------    --------------
             <S>               <C>                    <C>        <C>
             1 Year                   +14.81%         +28.51%        + 7.55%
             3 Years                  +15.59          +31.05         +10.30
             5 Years                  +10.96          +20.15         + 7.60
             10 Years                 +13.06          +18.72         + 9.21
             Lifetime*                + 9.74          +16.03            N/A
</TABLE>    
                      
                   *June 17, 1986, to November 30, 1997.     
- -------------------------------------------------------------------------------
DIVIDENDS,         The Fund expects to pay quarterly dividends from net in-
CAPITAL GAINS      vestment income. Net capital gains distributions, if any,
AND TAXES          will be made annually.
 
THE FUND WILL      Dividend and capital gains distributions may be automati-
PAY QUARTERLY      cally reinvested or received in cash. See "Choosing a Dis-
DIVIDENDS          tribution Option" for a description of these distribution
                   methods.
 
                   In addition, in order to satisfy certain distribution re-
                   quirements of the Tax Reform Act of 1986, the Fund may de-
                   clare special year-end dividend and capital gains distri-
                   butions during December. Such distributions, if received
                   by shareholders by January 31, are deemed to have been
                   paid by the Fund and received by shareholders on December
                   31 of the prior year.
 
12
<PAGE>
 
                   The Fund intends to continue to qualify for taxation as a
                   "regulated investment company" under the Internal Revenue
                   Code so that it will not be subject to federal income tax
                   to the extent its income is distributed to shareholders.
                   Dividends paid by the Fund from net investment income,
                   whether received in cash or reinvested in additional
                   shares, will be taxable to shareholders as ordinary in-
                   come. For corporate investors, a portion of dividends from
                   net investment income will qualify for the intercorporate
                   dividends-received deduction. However, the portion of the
                   dividends so qualified depends on the aggregate taxable
                   qualifying dividend income received by the Fund from do-
                   mestic (U.S.) sources.
                      
                   Distributions paid by the Fund from net long-term capital
                   gains, whether received in cash or reinvested in addi-
                   tional shares, are taxable as long-term capital gains, re-
                   gardless of the length of time you have owned shares in
                   the Fund. Long-term capital gains may be taxed at differ-
                   ent rates depending on how long the Fund held the securi-
                   ties. Capital gains distributions are made when the Fund
                   realizes net capital gains on sales of portfolio securi-
                   ties during the year. The Fund does not seek to realize
                   any particular amount of capital gains during a year;
                   rather, realized gains are a by-product of portfolio man-
                   agement activities. Consequently, capital gains distribu-
                   tions may be expected to vary considerably from year to
                   year; there will be no capital gains distributions in
                   years when the Fund realizes net capital losses.     
 
                   Note that if you accept capital gains distributions in
                   cash, instead of reinvesting them in additional shares,
                   you are in effect reducing the capital at work for you in
                   the Fund. Also, keep in mind that if you purchase shares
                   in the Fund shortly before the record date for a dividend
                   or capital gains distribution, a portion of your invest-
                   ment will be returned to you as a taxable distribution,
                   regardless of whether you are reinvesting your distribu-
                   tions or receiving them in cash.
 
                   The Fund will notify you annually as to the tax status of
                   dividend and capital gains distributions paid by the Fund.
 
A CAPITAL GAIN     A sale of shares of the Fund is a taxable event and may
OR LOSS MAY BE     result in a capital gain or loss. A capital gain or loss
REALIZED UPON      may be realized from an ordinary redemption of shares or
EXCHANGE OR        an exchange of shares between two mutual funds (or two
REDEMPTION         portfolios of a mutual fund).
 
                   Dividend distributions, capital gains distributions, and
                   capital gains or losses from redemptions and exchanges may
                   be subject to state and local taxes.
                      
                   The Fund is required to withhold 31% of taxable dividends,
                   capital gains distributions, and redemptions paid to
                   shareholders who have not complied with IRS taxpayer iden-
                   tification regulations. You may avoid this withholding re-
                   quirement by certifying on your Account Registration Form
                   your proper Social Security or taxpayer identification
                   Number and by certifying that you are not subject to
                   backup withholding.     
 
                   The Fund has obtained a Certificate of Authority to do
                   business as a foreign corporation in Pennsylvania and does
                   business and maintains an office in that state.
 
                                                                             13
<PAGE>
 
                   In the opinion of counsel, the shares of the Fund will be
                   exempt from Pennsylvania personal property taxes.
 
                   The tax discussion set forth above is included for general
                   information only. Prospective investors should consult
                   their own tax advisers concerning the tax consequences of
                   an investment in the Fund. The Fund is managed without re-
                   gard to tax ramifications.
- -------------------------------------------------------------------------------
   
THE SHARE PRICE    The Fund's share price, or "net asset value" per share, is
OF THE FUND        calculated by dividing the total assets of the Portfolio,
                   less all liabilities, by the total number of shares out-
                   standing. The net asset value is determined as of the
                   close of the New York Stock Exchange (generally 4:00 p.m.
                   Eastern time) on each day the exchange is open for trad-
                   ing.     
                      
                   Portfolio securities for which market quotations are read-
                   ily available (includes those securities listed on na-
                   tional securities exchanges, as well as those quoted on
                   the NASDAQ Stock Market) will be valued at the last quoted
                   sales price on the day the valuation is made. Such securi-
                   ties which are not traded on the valuation date are valued
                   at the mean of the bid and ask prices. Price information
                   on exchange-listed securities is taken from the exchange
                   where the security is primarily traded. Any foreign secu-
                   rities are valued at the latest quoted sales price avail-
                   able before the time when assets are valued. Securities
                   may be valued on the basis of prices provided by a pricing
                   service when such prices are believed to reflect the fair
                   market value of such securities.     
                      
                   Short-term instruments (those with remaining maturities of
                   60 days or less) may be valued at cost, plus or minus any
                   amortized discount or premium, which approximates market
                   value.     
                      
                   Bonds and other fixed income securities may be valued on
                   the basis of prices provided by a pricing service when
                   such prices are believed to reflect the fair market value
                   of such securities. The prices provided by a pricing serv-
                   ice may be determined without regard to bid or last sale
                   prices of each security, but take into account institu-
                   tional-size transactions in similar groups of securities
                   as well as any developments related to specific securi-
                   ties.     
                      
                   Other assets and securities for which no quotations are
                   readily available or which are restricted as to sale (or
                   resale) are valued by such methods as the Board of Direc-
                   tors deems in good faith to reflect fair value.     
                      
                   The share price for the Fund can be found daily in the mu-
                   tual fund listings of most major newspapers under the
                   heading of Vanguard Funds.     
                          
- -------------------------------------------------------------------------------
GENERAL            The Fund is a Maryland corporation. The Fund's Articles of
INFORMATION        Incorporation permit the Directors to issue 1,000,000,000
                   shares of common stock, with a $.001 par value. The Board
                   of Directors has the power to designate one or more clas-
                   ses ("Portfolios") of shares of common stock and to clas-
                   sify or reclassify any unissued shares with respect to
                   such Portfolios. Currently the Fund is offering one class
                   of shares.
 
14
<PAGE>
 
                   The shares of the Fund are fully paid and nonassessable;
                   have no preferences as to conversion, exchange, dividends,
                   retirement or other features; and have no pre-emptive
                   rights. Such shares have non-cumulative voting rights,
                   meaning that the holders of more than 50% of the shares
                   voting for the election of Directors can elect 100% of the
                   Directors if they so choose. A shareholder is entitled to
                   one vote for each full share held (and a fractional vote
                   for each fractional share held).
 
                   Annual meetings of shareholders will not be held except as
                   required by the Investment Company Act of 1940 and other
                   applicable law. If requested in writing by the holders of
                   not less than 10% of the outstanding shares of the Fund,
                   an annual meeting will be held to vote on the removal of a
                   Director or Directors of the Fund.
 
                   All securities and cash are held by CoreStates Bank, N.A.,
                   Philadelphia, PA. The Vanguard Group, Inc., Valley Forge,
                   PA, serves as the Fund's Transfer and Dividend Disbursing
                   Agent. Price Waterhouse LLP serves as independent accoun-
                   tants for the Fund and will audit its financial statements
                   annually. The Fund is not involved in any litigation.
- -------------------------------------------------------------------------------
 
                                                                             15
<PAGE>
 
                               SHAREHOLDER GUIDE
 
   
OPENING AN         You may open a regular (non-retirement) account, either by
ACCOUNT AND        mail or wire. Simply complete and return an Account Regis-
PURCHASING         tration Form and any required legal documentation, indi-
SHARES             cating the amount you wish to invest. Your purchase must
                   be equal to or greater than the $3,000 minimum initial in-
                   vestment requirement ($1,000 for Uniform Gifts/Transfers
                   to Minors Act accounts and IRAs, $500 minimum for an Edu-
                   cation IRA). You must open a new Individual Retirement Ac-
                   count by mail (IRAs may not be opened by wire) using a
                   Vanguard IRA Adoption Agreement. Your purchase must be
                   equal to or greater than the $1,000 minimum initial in-
                   vestment requirement, but no more than $2,000 if you are
                   making a regular IRA contribution. Rollover contributions
                   are generally limited to the amount withdrawn within the
                   past 60 days from an IRA or other qualified retirement
                   plan. If you need assistance with the form or have any
                   questions about this Fund, please call our Investor Infor-
                   mation Department at 1-800-662-7447. Note: For other types
                   of account registrations (e.g., corporations, associa-
                   tions, other organizations, trusts or powers of attorney),
                   please call us to determine which additional forms you may
                   need.     
 
                   The Fund's shares are purchased at the next-determined net
                   asset value after your investment has been received. The
                   Fund is offered on a no-load basis (i.e., there are no
                   sales commissions or 12b-1 fees).
 
PURCHASE           1) Because of the risks associated with common stock in-
RESTRICTIONS          vestments, the Fund is intended to be a long-term in-
                      vestment vehicle and is not designed to provide invest-
                      ors with a means of speculating on short-term stock
                      market movements. Consequently, the Fund reserves the
                      right to reject any specific purchase (and exchange
                      purchase) request. The Fund also reserves the right to
                      suspend the offering of shares for a period of time.
 
                   2) Vanguard will not accept third-party checks to purchase
                      shares of the Fund. Please be sure your purchase check
                      is made payable to The Vanguard Group.
   
ADDITIONAL         Subsequent investments to regular accounts may be made by
INVESTMENTS        mail ($100 minimum), wire ($1,000 minimum), exchange from
                   another Vanguard Fund account ($100 minimum), or Vanguard
                   Fund Express. Subsequent investments to Individual Retire-
                   ment Accounts may be made by mail ($100 minimum) or ex-
                   change from another Vanguard Fund account. In some in-
                   stances, contributions may be made by wire or Vanguard
                   Fund Express. Please call us for more information on these
                   options.     
                   -----------------------------------------------------------
 
16
<PAGE>
 
 
                                                     ADDITIONAL INVESTMENTS
                       NEW ACCOUNT                    TO EXISTING ACCOUNTS
    
PURCHASING BY      Please include the               Additional investments
MAIL Complete      amount of your initial           should include the Invest-
and sign the       investment on the reg-           by-Mail remittance form
enclosed Account   istration form, make             attached to your Fund con-
Registration       your check payable to            firmation statements.
Form               The Vanguard Group-82            Please make your check
                   and mail to:                     payable to The Vanguard
                                                    Group-82, write your ac-
                   THE VANGUARD GROUP               count number on your check
                   P.O. BOX 2600                    and, using the return en-
                   VALLEY FORGE, PA 19482-          velope provided, mail to
                   2600                             the address indicated on
                                                    the invest-by-Mail Form.
                                                    
For express or     THE VANGUARD GROUP               All written requests       
registered mail,   455 DEVON PARK DRIVE             should be mailed to one of 
send to:           WAYNE, PA 19087-1815             the addresses indicated    
                                                    for new accounts. Do not   
                                                    send registered or express 
                                                    mail to the post office     
                                                    box address.      
                                                                                
                   ------------------------------------------------------------
PURCHASING BY                  CORESTATES BANK, N.A.
WIRE Money                     ABA 031000011
should be wired                CORESTATES NO. 0101 9897
to:                            ATTN: VANGUARD
 
BEFORE WIRING                  VANGUARD CONVERTIBLE SECURITIES FUND
Please contact                 ACCOUNT NUMBER
Client Services                ACCOUNT REGISTRATION
(1-800-662-2739)
 
 
                   To assure proper receipt, please be sure your bank includes
                   the name of the Fund selected, the account number Vanguard
                   has assigned to you and the eight-digit CoreStates number.
                   If you are opening a new account, please complete the Ac-
                   count Registration Form and mail it to the "New Account"
                   address above after completing your wire arrangement. NOTE:
                   Federal Funds wire purchase orders will be accepted only
                   when the Fund and Custodian Bank are open for business.
                   ------------------------------------------------------------
PURCHASING BY      You may open a new account or purchase additional shares by
EXCHANGE (from a   making an exchange from an existing Vanguard account.
Vanguard           Please call our Client Services Department at 1-800-662-
account)           2739. The new account will have the same registration as
                   the existing account. However, the Fund reserves the right
                   to refuse any exchange purchase request.
                   ------------------------------------------------------------
PURCHASING BY      The Fund Express Special Purchase option lets you move
FUND EXPRESS       money from your bank account to your Vanguard account on an
                   "as needed" basis. Or if you choose the Automatic Invest-
Special Purchase   ment option, money will be moved automatically from your
and Automatic      bank account to your Vanguard account on the schedule
Investment         (monthly, bimonthly [every
 
                                                                              17
<PAGE>
 
                   other month], quarterly, semi-annually or annually) you
                   select. To establish these Fund Express options, please
                   provide the appropriate information on the Account Regis-
                   tration Form. We will send you a confirmation of your Fund
                   Express service; please wait two weeks before using the
                   service.
- -------------------------------------------------------------------------------
   
CHOOSING A         You must select one of four distribution options: 
DISTRIBUTION
OPTION             1. AUTOMATIC REINVESTMENT OPTION--Both dividend and capi-  
                      tal gains distributions will be reinvested in addi-      
                      tional Fund shares. This option will be selected for     
                      you automatically unless you specify one of the other    
                      options. 
                                                                               
                   2. CASH DIVIDEND OPTION--Your dividends will be paid in     
                      cash and your capital gains will be reinvested in addi-  
                      tional Fund shares.                                      

                   3. CASH CAPITAL GAIN OPTION--Your capital gains distribu-   
                      tions will be paid in cash and your dividends will be    
                      reinvested in additional Fund shares. 

                   4. ALL CASH OPTION--Both dividend and capital gains dis-    
                      tributions will be paid in cash.                         
  
                   You may change your option by calling our Client Services
                   Department (1-800-662-2739).
                      
                   If a shareholder has chosen to receive dividend and/or
                   capital gains distributions in cash, and the postal or
                   other delivery service is unable to deliver checks to the
                   shareholder's address of record, we will change the dis-
                   tribution option so that all dividends and other distribu-
                   tions are automatically reinvested in additional shares.
                   We will not pay interest on uncashed distribution checks.
                          
                   In addition, an option to invest your cash dividend and/or
                   capital gains distributions in another Vanguard Fund ac-
                   count is available. Please call our Client Services De-
                   partment (1-800-662-2739) for information. You may also
                   elect Vanguard Dividend Express which allows you to trans-
                   fer your cash dividend and/or capital gains distributions
                   automatically to your bank account. Please see "Other Van-
                   guard Services" for more information.     
- -------------------------------------------------------------------------------
TAX CAUTION        Under Federal tax laws, the Fund is required to distribute
                   net capital gains and dividend income to Fund sharehold-
INVESTORS SHOULD   ers. These distributions are made to all shareholders who
ASK ABOUT THE      own Fund shares as of the distribution's record date, re-
TIMING OF          gardless of how long the shares have been owned. Purchas-
CAPITAL GAINS      ing shares just prior to the record date could have a sig-
AND DIVIDEND       nificant impact on your tax liability for the year. For
DISTRIBUTIONS      example, if you purchase shares immediately prior to the
BEFORE INVESTING   record date of a sizable capital gain or income dividend
                   distribution, you will be assessed taxes on the amount of
                   the capital gain and/or dividend distribution later paid
                   even though you owned the Fund shares for just a short pe-
                   riod of time. (Taxes are due on the distributions even if
                   the dividend or gain is reinvested in additional Fund
                   shares.) While the total value of your investment will be
                   the same after the distribution--the amount of the distri-
                   bution will offset the drop in the net asset value of the
                   shares--you should be aware of the tax implications the
                   timing of your purchase may have.
 
                 
18
<PAGE>
 
                      
                   Prospective investors should, therefore, inquire about po-
                   tential distributions before investing. The Fund's annual
                   capital gains distribution normally occurs in December,
                   while income dividends are generally paid quarterly in
                   March, June, September and December. In addition, the Fund
                   may occasionally be required to make supplemental dividend
                   or capital gains distributions at some other time during
                   the year. For additional information on distributions and
                   taxes, see the section titled "Dividends, Capital Gains,
                   and Taxes."     
- -------------------------------------------------------------------------------
IMPORTANT          The easiest way to establish optional Vanguard services on
INFORMATION        your account is to select the options you desire when you
                   complete your Account Registration Form.
            
ESTABLISHING       IF YOU WISH TO ADD SHAREHOLDER OPTIONS LATER, YOU MAY NEED
OPTIONAL           TO PROVIDE VANGUARD WITH ADDITIONAL INFORMATION AND A SIG-
SERVICES           NATURE GUARANTEE. PLEASE CALL OUR CLIENT SERVICES DEPART-
                   MENT (1-800-662-2739) FOR FURTHER ASSISTANCE.
 
SIGNATURE          For our mutual protection, we may require a signature
GUARANTEES         guarantee on certain written transaction requests. A sig-
                   nature guarantee verifies the authenticity of your signa-
                   ture, and may be obtained from banks, brokers and any
                   other guarantor that Vanguard deems acceptable. A SIGNA-
                   TURE GUARANTEE CANNOT BE PROVIDED BY A NOTARY PUBLIC.
 
CERTIFICATES       Share certificates will be issued upon request. If a cer-
                   tificate is lost, you may incur an expense to replace it.
                       
BROKER/DEALER      If you purchase shares in Vanguard Funds through a regis-
PURCHASES          tered broker/dealer or investment adviser, the
                   broker/dealer or adviser may charge a service fee.     
   
CANCELLING         The Fund will not cancel any trade (e.g., purchase, ex-
TRADES             change or redemption) believed to be authentic, once the
                   trade request has been received in writing or by tele-
                   phone.     
   
ELECTRONIC         You may receive a prospectus for the Fund or any of the
PROSPECTUS         Vanguard Funds in an electronic format through Vanguard's
DELIVERY           website at www.vanguard.com. For additional information
                   please see "Other Vanguard Services--Computer Access."
                       
- -------------------------------------------------------------------------------
WHEN YOUR          Your trade date is the date on which your account is cred-
ACCOUNT WILL BE    ited. If your purchase is made by check, Federal Funds
CREDITED           wire or exchange and is received by the close of regular
                   trading on the New York Stock Exchange (generally 4:00
                   p.m. Eastern time), your trade date is the day of receipt.
                   If your purchase is received after the close of regular
                   trading on the Exchange, your trade date is the next busi-
                   ness day. Your shares are purchased at the net asset value
                   determined on your trade date.
 
                   In order to prevent lengthy processing delays caused by
                   the clearing of foreign checks, Vanguard will only accept
                   a foreign check which has been drawn in U.S. dollars and
                   has been issued by a foreign bank with a U.S. correspon-
                   dent bank. The name of the U.S. correspondent bank must be
                   printed on the face of the foreign check.
 
                   The Fund reserves the right to suspend the offering of
                   shares for a period of time. The Fund also reserves the
                   right to reject any specific purchase request.
- -------------------------------------------------------------------------------
 
                                                                             19
<PAGE>
 
   
SELLING YOUR       You may withdraw any portion of the funds in your account
SHARES             by redeeming shares at any time. (Please see "Important
                   Redemption Information.") You generally may initiate a re-
                   quest by writing or by telephoning. Your redemption pro-
                   ceeds are normally mailed within two business days after
                   the receipt of the request in Good Order. No interest will
                   accrue on amounts represented by uncashed redemption
                   checks.     
                   -----------------------------------------------------------
   
SELLING BY MAIL    Requests should be mailed to THE VANGUARD GROUP, VANGUARD
                   CONVERTIBLE SECURITIES FUND, P.O. BOX 1120, VALLEY FORGE,
                   PA 19482-1120. (For express or registered mail, send your
                   request to The Vanguard Group, Vanguard Convertible Secu-
                   rities Fund, 455 Devon Park Drive, Wayne, PA 19087-1815.)
                       
                   The redemption price of shares will be the Fund's net as-
                   set value next determined after Vanguard has received all
                   required documents in Good Order.
                   -----------------------------------------------------------
DEFINITION OF      GOOD ORDER means that the request includes the following:
GOOD ORDER   
                   1. The account number and Fund name.
                   2. The amount of the transaction (specified in dollars or
                      shares).
                   3. The signatures of all owners exactly as they are regis-
                      tered on the account.
                   4. Any required signature guarantees.
                      
                   5. Other supporting legal documentation that may be re-
                      quired, in the case of estates, corporations, trusts,
                      and certain other accounts.     
                   6. Any certificates that you are holding for the account.
 
                   IF YOU HAVE ANY QUESTIONS ABOUT THIS DEFINITION AS IT PER-
                   TAINS TO YOUR REQUEST, PLEASE CALL OUR CLIENT SERVICES DE-
                   PARTMENT AT 1-800-662-2739.
                   -----------------------------------------------------------
   
SELLING BY         To sell shares by telephone, you or your pre-authorized
TELEPHONE          representative may call our Client Services Department at
                   1-800-662-2739. The proceeds will be sent to you by mail.
                   PLEASE NOTE: As a protection against fraud, your telephone
                   mail redemption privilege will be suspended for 15 calen-
                   dar days following any expedited address change to your
                   account. An expedited address change is one that is made
                   by telephone or in writing, without the signatures of all
                   account owners. Please see "Important Information About
                   Telephone Transactions."     
                   -----------------------------------------------------------
SELLING BY FUND    If you select the Fund Express Automatic Withdrawal op-
EXPRESS            tion, money will be automatically moved from your Vanguard
                   Fund account to your bank account according to the sched-
Automatic          ule you have selected. The Special Redemption option lets
Withdrawal &       you move money from your Vanguard account to your bank ac-
Special            count on an "as needed" basis. To establish these Fund Ex-
Redemption         press options, please provide the appropriate information
                   on the Account Registration Form. We will send you a con-
                   firmation of your Fund Express service; please wait two
                   weeks before using the service.
                   -----------------------------------------------------------
SELLING BY         You may sell shares of the Fund by making an exchange to
EXCHANGE           another Vanguard Fund account. Please see "Exchanging Your
                   Shares" for details.
                   -----------------------------------------------------------
 
20
<PAGE>
 
IMPORTANT          Shares purchased by check or Fund Express may be redeemed
REDEMPTION         at any time. However, your redemption proceeds will not be
INFORMATION        paid until payment for the purchase is collected, which
                   may take up to ten calendar days.
                   -----------------------------------------------------------
DELIVERY OF        Redemption requests received by telephone prior to the
REDEMPTION         close of regular trading on the New York Stock Exchange
PROCEEDS           are processed on the day of receipt and the redemption
                   proceeds are normally sent on the following business day.
                      
                   Redemption requests received by telephone after the close
                   of trading on the New York Stock Exchange (generally 4:00
                   p.m. Eastern time) are processed on the business day fol-
                   lowing receipt and the proceeds are normally sent on the
                   second business day following receipt.     
                      
                   Redemption proceeds must be sent to you within seven days
                   of receipt of your request in Good Order except as de-
                   scribed above in Important Redemption Information.     
 
                   If you experience difficulty in making a telephone redemp-
                   tion during periods of drastic economic or market changes,
                   your redemption request may be made by regular or express
                   mail. It will be implemented at the net asset value next
                   determined after your request has been received by Van-
                   guard in Good Order. The Fund reserves the right to revise
                   or terminate the telephone redemption privilege at any
                   time.
 
                   The Fund may suspend the redemption right or postpone pay-
                   ment at times when the New York Stock Exchange is closed
                   or under any emergency circumstances as determined by the
                   United States Securities and Exchange Commission.
 
                   If the Board of Directors determines that it would be det-
                   rimental to the best interests of the Fund's remaining
                   shareholders to make payment in cash, the Fund may pay re-
                   demption proceeds in excess of $250,000 in whole or in
                   part by a distribution in kind of readily marketable secu-
                   rities.
                   -----------------------------------------------------------
VANGUARD'S         If you make a redemption from a qualifying account, Van-
AVERAGE COST       guard will send you an Average Cost Statement which pro-
STATEMENT          vides you with the tax basis of the shares you redeemed.
                   Please see "Statements and Reports" for additional infor-
                   mation.
                   -----------------------------------------------------------
   
LOW BALANCE FEE    Due to the relatively high cost of maintaining smaller ac-
AND MINIMUM        counts, the Fund will automatically deduct a $10 annual
ACCOUNT BALANCE    fee in either June or December from non-retirement ac-
REQUIREMENT        counts with balances falling below $2,500 ($500 for Uni-
                   form Gifts/Transfers to Minors Act accounts). The fee gen-
                   erally will be waived for investors whose aggregate Van-
                   guard assets exceed $50,000.     
 
                   In addition, the Fund reserves the right to liquidate any
                   non-retirement account that is below the minimum initial
                   investment amount of $3,000. If at any time the total in-
                   vestment does not have a value of at least $3,000, you may
                   be notified that your account is below the Fund's minimum
                   account balance requirement. You
 
                                                                             21
<PAGE>
 
                   would then be allowed 60 days to make an additional in-
                   vestment before the account is liquidated. Proceeds would
                   be promptly paid to the registered shareholder.
 
                   Vanguard will not liquidate your account if it has fallen
                   below $3,000 solely as a result of declining markets
                   (i.e., a decline in a Fund's net asset value).
- -------------------------------------------------------------------------------
EXCHANGING YOUR    Should your investment goals change, you may exchange your
SHARES             shares of Vanguard Convertible Securities Fund for those
                   of other available Vanguard Funds.
   
EXCHANGING BY      When exchanging shares by telephone, please have ready the
TELEPHONE          Fund name, account number, Social Security Number or em-
                   ployer identification number listed on the account, and
Call Client        the exact name and address in which the account is regis-
Services (1-800-   tered. Requests for telephone exchanges received prior to
662-2739)          the close of trading on the New York Stock Exchange (gen-
                   erally 4:00 p.m. Eastern time) are processed at the close
                   of business that same day. Requests received after the
                   close of the Exchange are processed the next business day.
                   TELEPHONE EXCHANGES ARE NOT ACCEPTED INTO OR FROM NON-RE-
                   TIREMENT INVESTMENTS IN VANGUARD INDEX TRUST, VANGUARD
                   BALANCED INDEX FUND, VANGUARD INTERNATIONAL EQUITY INDEX
                   FUND, VANGUARD REIT INDEX PORTFOLIO, VANGUARD TOTAL INTER-
                   NATIONAL PORTFOLIO, AND VANGUARD GROWTH AND INCOME PORTFO-
                   LIO. If you experience difficulty in making a telephone
                   exchange, your exchange request may be made by regular or
                   express mail, and it will be implemented at the closing
                   net asset value on the date received by Vanguard provided
                   the request is received in Good Order.     
                   -----------------------------------------------------------
   
EXCHANGING BY      Please be sure to include on your exchange request the
MAIL               name and account number of your current Fund, the name of
                   the Fund you wish to exchange into, the amount you wish to
                   exchange, and the signatures of all registered account
                   holders. Send your request to THE VANGUARD GROUP, VANGUARD
                   CONVERTIBLE SECURITIES FUND, P.O. BOX 1120, VALLEY FORGE,
                   PA 19482-1120. (For express or registered mail, send your
                   request to Vanguard Financial Center, Vanguard Convertible
                   Securities Fund, 455 Devon Park Drive, Wayne, PA 19087-
                   1815.)     
                   -----------------------------------------------------------
                   
EXCHANGING         You may use your personal computer to exchange shares of
ONLINE             most Vanguard funds by accessing our website
                   (www.vanguard.com). To establish this service for your ac-
                   count, you must first register through the website. We
                   will then send to you, by mail, an account access password
                   that will enable you to make online exchanges.     
                      
                   The Vanguard funds that you cannot purchase or sell
                   through online exchange are VANGUARD INDEX TRUST, VANGUARD
                   BALANCED INDEX FUND, VANGUARD INTERNATIONAL EQUITY INDEX
                   FUND, VANGUARD REIT INDEX PORTFOLIO, VANGUARD TOTAL INTER-
                   NATIONAL PORTFOLIO, AND VANGUARD GROWTH AND INCOME PORTFO-
                   LIO (formerly known as Vanguard Quantitative Portfolios).
                   These funds do permit online exchanges within IRAs and
                   other retirement accounts.     
                   -----------------------------------------------------------
 
22
<PAGE>
 
IMPORTANT          Before you make an exchange, you should consider the fol-
EXCHANGE           lowing:
INFORMATION
                   . Please read the Fund's prospectus before making an ex-
                     change. For a copy and for answers to any questions you
                     may have, call our Investor Information Department (1-
                     800-662-7447).
 
                   . An exchange is treated as a redemption and a purchase.
                     Therefore, you could realize a taxable gain or loss on
                     the transaction.
                      
                   . Exchanges by telephone are accepted only if the regis-
                     trations and the taxpayer identification numbers of the
                     two accounts are identical.     
                      
                   . To exchange into an account with a different registra-
                     tion (including a different name, address, or taxpayer
                     identification number), you must provide Vanguard with
                     written instructions that include the guaranteed signa-
                     tures of all current account owners.     
 
                   . The shares to be exchanged must be on deposit and not
                     held in certificate form.
 
                   . New accounts are not currently accepted in
                     Vanguard/Windsor Fund.
 
                   . The redemption price of shares redeemed by exchange is
                     the net asset value next determined after Vanguard has
                     received the required documentation in Good Order.
 
                   . When opening a new account by exchange, you must meet
                     the minimum investment requirement of the new Fund.
                      
                   Every effort will be made to maintain the exchange privi-
                   lege. However, the Fund reserves the right to revise or
                   terminate its provisions, limit the amount of, or reject
                   any exchange, as deemed necessary, at any time.     
 
                   The exchange privilege is only available in states in
                   which shares of the Fund are registered for sale. The
                   Fund's shares are currently registered for sale in all 50
                   states and the Fund intends to maintain such registration.
- -------------------------------------------------------------------------------
EXCHANGE           The Fund's exchange privilege is not intended to afford
PRIVILEGE          shareholders a way to speculate on short-term movements in
LIMITATIONS        the market. Accordingly, in order to prevent excessive use
                   of the exchange privilege that may potentially disrupt the
                   management of the Fund and increase transaction costs, the
                   Fund has established a policy of limiting excessive ex-
                   change activity.
                      
                   Exchange activity generally will not be deemed excessive
                   if limited to two substantive exchange redemptions (at
                   least 30 days apart) from the Fund during any twelve month
                   period. "Substantive" means either a dollar amount or a
                   series of movements between Vanguard funds that Vanguard
                   determines, in its sole discretion, could have an adverse
                   impact on the management of the Fund. Notwithstanding
                   these limitations, the Fund reserves the right to reject
                   any purchase request (including exchange purchases from
                   other Vanguard portfolios) that is reasonably deemed to be
                   disruptive to efficient portfolio management.     
- -------------------------------------------------------------------------------
 
                                                                             23
<PAGE>
                 
   
IMPORTANT          The ability to initiate redemptions (except wire or Fund
INFORMATION        Express redemptions) and exchanges by telephone is auto-
ABOUT TELEPHONE    matically established on your account unless you request
TRANSACTIONS       in writing that telephone transactions on your account not
                   be permitted.     
 
                   To protect your account from losses resulting from unau-
                   thorized or fraudulent telephone instructions, Vanguard
                   adheres to the following security procedures:
 
                   1. SECURITY CHECK. To request a transaction by telephone,
                      the caller must know (i) the name of the Fund; (ii) the
                      10-digit account number; (iii) the exact name and ad-
                      dress used in the registration; and (iv) the Social Se-
                      curity or employer identification number listed on the
                      account.
 
                   2. PAYMENT POLICY. The proceeds of any telephone redemp-
                      tion made by mail will be made payable to the regis-
                      tered shareowner and mailed to the address of record,
                      only.
 
                   Neither the Fund nor Vanguard will be responsible for the
                   authenticity of transaction instructions received by tele-
                   phone, provided that reasonable security procedures have
                   been followed. Vanguard believes that the security proce-
                   dures described above are reasonable, and that if such
                   procedures are followed, you will bear the risk of any
                   losses resulting from unauthorized or fraudulent telephone
                   transactions on your account.
- -------------------------------------------------------------------------------
   
TRANSFERRING       You may transfer the registration of any of your Fund
REGISTRATION       shares to another person by completing a transfer form and
                   sending it to: THE VANGUARD GROUP, ATTENTION: TRANSFER DE-
                   PARTMENT, P.O. BOX 1110, VALLEY FORGE, PA 19482-1110. AT-
                   TENTION: TRANSFER DEPARTMENT. The request must be in Good
                   Order. BEFORE MAILING YOUR REQUEST, PLEASE CALL OUR CLIENT
                   SERVICES DEPARTMENT (1-800-662-2739) FOR FULL INSTRUC-
                   TIONS.     
- -------------------------------------------------------------------------------
STATEMENTS AND     Vanguard will send you a confirmation statement each time
REPORTS            you initiate a transaction in your account (except for
                   checkwriting redemptions from Vanguard money market ac-
                   counts). You will also receive a comprehensive account
                   statement at the end of each calendar quarter. The fourth-
                   quarter statement will be a year-end statement, listing
                   all transaction activity for the entire calendar year.
                      
                   Vanguard's Average Cost Statement provides you with the
                   average cost of shares redeemed from your account during
                   the calendar year, using the average cost single category
                   method. This service is available for most taxable ac-
                   counts opened since January 1, 1986. In general, investors
                   who redeemed shares from a qualifying Vanguard account may
                   expect to receive their Average Cost Statement along with
                   their Portfolio Summary Statement. Please call our Client
                   Services Department (1-800-662-2739) for information.     
 
                   Financial reports on the Fund will be mailed to you semi-
                   annually, according to the Fund's fiscal year-end.
- -------------------------------------------------------------------------------
 
24
<PAGE>
 
OTHER VANGUARD     For more information about any of these services, please
SERVICES           call our Investor Information Department at 1-800-662-
                   7447.
 
VANGUARD DIRECT    With Vanguard's Direct Deposit Service, most U.S. Govern-
DEPOSIT SERVICE    ment checks (including Social Security and military pen-
                   sion checks) and private payroll checks may be automati-
                   cally deposited into your Vanguard Fund account. Separate
                   brochures and forms are available for direct deposit of
                   U.S. Government and private payroll checks.
 
VANGUARD           Vanguard's Automatic Exchange Service allows you to move
AUTOMATIC          money automatically among your Vanguard Fund accounts. For
EXCHANGE SERVICE   instance, the service can be used to "dollar cost average"
                   from a money market portfolio into a stock or bond fund or
                   to contribute to an IRA or other retirement plan. Please
                   contact our Client Services Department at 1-800-662-2739
                   for additional information.
 
VANGUARD FUND      Vanguard's Fund Express allows you to transfer money be-
EXPRESS            tween your Fund account and your account at a bank, sav-
                   ings and loan association, or a credit union that is a
                   member of the Automated Clearing House (ACH) system. You
                   may elect this service on the Account Registration Form or
                   call our Investor Information Department (1-800-662-7447)
                   for a Fund Express application.
 
                   Special rules govern how your Fund Express purchases or
                   redemptions are credited to your account. In addition,
                   some services of Fund Express cannot be used with specific
                   Vanguard Funds. For more information, please refer to the
                   Vanguard Fund Express brochure.
   
VANGUARD           Vanguard's Dividend Express allows you to transfer your
DIVIDEND EXPRESS   dividend and/or capital gains distributions automatically
                   from your Fund account, one business day after the Fund's
                   payable date, to your account at a bank, savings and loan
                   association, or a credit union that is a member of the Au-
                   tomated Clearing House (ACH) system. You may elect this
                   service on the Account Registration Form or call our
                   Investor Information Department (1-800-662-7447) for a
                   Vanguard Dividend Express application.     
 
                   Vanguard's Tele-Account is a convenient, automated service
VANGUARD           that provides share price, price change and yield quota-
TELE-ACCOUNT(R)    tions on Vanguard Funds through any TouchTone(TM) tele-
                   phone. This service also lets you obtain information about
                   your account balance, your last transaction, and your most
                   recent dividend or capital gains payment. In addition, you
                   may perform investment exchanges of Vanguard Fund shares
                   and redemptions by check using Tele-Account. To contact
                   Vanguard's Tele-Account service, dial 1-800-ON-BOARD (1-
                   800-662-6273). A brochure offering detailed operating in-
                   structions is available from our Investor Information De-
                   partment (1-800-662-7447).     
COMPUTER ACCESS
    
VANGUARD ONLINE    Use your personal computer to learn more about Vanguard's  
www.vanguard.com   funds and services; keep in touch with your Vanguard ac-   
                   counts; map out a long-term investment strategy; initiate   
                   certain transactions; and ask questions, make suggestions,  
                   and send messages to Vanguard.                              
                                                                               

                                                                             25
<PAGE>
 
                      
                   Our education-oriented website provides timely news and
                   information about Vanguard's funds and services; an online
                   "university" that offers a variety of mutual fund classes;
                   and easy-to-use, interactive tools to help you create your
                   own investment and retirement strategies.     
                          
- -------------------------------------------------------------------------------
 
26
<PAGE>
 
[LOGO OF VANGUARD APPEARS HERE]
 
- ---------------
 
THE VANGUARD GROUP
          
P.O. Box 2600     
Valley Forge, PA 19482
 
INVESTOR INFORMATION DEPARTMENT:
1-800-662-7447
 
CLIENT SERVICES DEPARTMENT:
1-800-662-2739
 
TELE-ACCOUNT FOR 24-HOUR ACCESS:
1-800-662-6273 (ON-BOARD)
 
TELECOMMUNICATION SERVICE FOR THE HEARING-IMPAIRED:
1-800-662-2738
 
TRANSFER AGENT:
The Vanguard Group, Inc.
          
P.O. Box 2600     
Valley Forge, PA 19482

                        [LOGO OF VANGUARD APPEARS HERE]
 
                              P R O S P E C T U S
                                 
                              MARCH 20, 1998     
 
 
 
                                  A member of
                             THE VANGUARD GROUP(R)
 
PI82
<PAGE>
 
                                    PART B
 
                  VANGUARD CONVERTIBLE SECURITIES FUND, INC.
 
                      STATEMENT OF ADDITIONAL INFORMATION
                                 
                              MARCH 20, 1998     
   
  This Statement is not a prospectus but should be read in conjunction with
the Fund's current Prospectus dated March 20, 1998. To obtain the Prospectus
please call:     
 
                        INVESTOR INFORMATION DEPARTMENT
                                1-800-662-7447
 
                               TABLE OF CONTENTS
 
<TABLE>   
<CAPTION>
                                                                            PAGE
                                                                            ----
<S>                                                                         <C>
Investment Limitations.....................................................  B-1
Purchase of Shares.........................................................  B-2
Redemption of Shares.......................................................  B-2
Management of the Fund.....................................................  B-3
Directors and Officers.....................................................  B-5
Investment Advisory Services...............................................  B-7
Portfolio Transactions.....................................................  B-9
General Information........................................................ B-10
Yield and Total Return..................................................... B-10
Comparative Indexes........................................................ B-10
Financial Statements....................................................... B-13
Appendix--Description of Securities and Ratings............................ B-14
</TABLE>    
 
                            INVESTMENT LIMITATIONS
 
  The following restrictions are fundamental policies and cannot be changed
without approval of the holders of a majority of the outstanding shares of the
Fund or, if less, 67% of the shares represented at a meeting of shareholders
at which the holders of 50% or more of the shares are represented. The Fund
may not under any circumstances:
 
    1. Borrow money, except that the Fund may borrow from banks (or through
  reverse repurchase agreements), for temporary or emergency (not leveraging)
  purposes, including the meeting of redemption requests which might other-
  wise require the untimely disposition of securities, in an amount not ex-
  ceeding 10% of the value of the Fund's total assets (including the amount
  borrowed) at the time the borrowing is made. Whenever borrowings exceed 5%
  of the value of the Fund's total assets, the Fund will not make any addi-
  tional investments;
 
    2. With respect to 75% of the value of its total assets, purchase the se-
  curities of any issuer (except obligations of the United States government
  and its instrumentalities) if as a result the Fund would hold more than 10%
  of the outstanding voting securities of the issuer, or more than 5% of the
  value of the Fund's total assets would be invested in the securities of
  such issuer;
 
    3. Invest for the purpose of exercising control of management of any com-
  pany;
 
    4. Invest in securities of other investment companies, except as they may
  be acquired as part of a merger, consolidation or acquisition of assets or
  otherwise to the extent permitted by Section 12 of the Investment Company
  Act of 1940 (the "1940 Act"). The Fund will invest only in investment com-
  panies which have investment objectives and investment policies consistent
  with those of the Fund;
 
                                                                            B-1
<PAGE>
 
    5. Engage in the business of underwriting securities issued by other per-
  sons, except to the extent that the Fund may technically be deemed to be an
  underwriter under the Securities Act of 1933, as amended, in disposing of
  investment securities;
 
    6. Purchase or otherwise acquire any security if, as a result, more than
  15% of its net assets would be invested in securities that are illiquid
  (including the Fund's investment in The Vanguard Group, Inc.);
 
    7. Invest in commodities or real estate, although the Fund may purchase
  and sell securities of companies which deal in real estate, or interests
  therein, and the Fund may purchase covered call options as described in the
  prospectus;
 
    8. Purchase securities on margin or sell any securities short;
 
    9. Invest more than 5% of the assets of the Fund, at the time of invest-
  ment, in the securities of any issuers which have (with predecessors) a
  record of less than three years' continuous operation;
 
    10. Purchase or retain any security if (i) one or more officers, direc-
  tors or partners of the Fund or its investment adviser individually own or
  would own, directly or beneficially, more than 1/2 of 1 per cent of the se-
  curities of such issuer, and (ii) in the aggregate such persons own or
  would own more than 5% of such securities;
 
    11. Make loans except (i) by purchasing bonds, debentures or similar ob-
  ligations (including repurchase agreements, subject to the limitation de-
  scribed in (6) above), which are publicly distributed, and (ii) by lending
  its securities to banks, brokers, dealers and other financial institutions
  so long as such loans are not inconsistent with the Investment Company Act
  or the Rules and Regulations or interpretations of the Securities and Ex-
  change Commission (the "Commission") thereunder;
 
    12. Pledge, mortgage, or hypothecate any of its assets to an extent
  greater than 5% of its total assets;
 
    13. Invest directly in interests in oil, gas or other mineral exploration
  or development programs; and
 
    14. Invest more than 25% of the value of its total assets in any one in-
  dustry.
 
  The above mentioned investment limitations are considered at the time in-
vestment securities are purchased. Notwithstanding these limitations, the Fund
may own all or any portion of the securities of, or make loans to, or contrib-
ute to the costs or other financial requirements of any company which will be
wholly-owned by the Fund and one or more other investment companies and is
primarily engaged in the business of providing, at-cost, management, adminis-
trative, distribution or related services to the Fund and other investment
companies. See "The Vanguard Group."
 
                              PURCHASE OF SHARES
 
  The Fund reserves the right in its sole discretion (i) to suspend the offer-
ing of its shares, (ii) to reject purchase orders when in the judgment of man-
agement such rejection is in the best interest of the Fund, and (iii) to re-
duce or waive the minimum investment for or any other restrictions on initial
and subsequent investments for certain fiduciary accounts or under circum-
stances where certain economies can be achieved in sales of the Fund's shares.
 
                             REDEMPTION OF SHARES
 
  The Fund may suspend redemption privileges or postpone the date of payment
for redeemed shares (i) during any period that the New York Stock Exchange is
closed, or trading on the Exchange is re-
 
B-2
<PAGE>
 
stricted, as determined by the Commission; (ii) during any period when an
emergency exists, as defined by the rules of the Commission, as a result of
which it is not reasonably practicable for the Fund to dispose of securities
owned by it or fairly determine the value of its assets; and (iii) for such
other periods as the Commission may permit.
 
  No charge is made by the Fund for redemptions. Any redemption may be more or
less than the shareholder's cost, depending on the current market value of the
securities held by the Fund.
 
  The Fund has made an election with the Commission to pay in cash all redemp-
tions requested by any shareholder of record limited in amount during any 90-
day period to the lesser of $250,000 or 1% of the net assets of the Fund at
the beginning of such period. Such commitment is irrevocable without the prior
approval of the Commission. Redemptions in excess of the above limits may be
paid in whole or in part in investment securities or in cash, as the Directors
may deem advisable; however, payment will be made wholly in cash unless the
Directors believe that economic or market conditions exist which would make
such a practice detrimental to the best interests of the Fund. If redemptions
are paid in investment securities, such securities will be valued as set forth
in the Prospectus under "The Fund's Share Price," and a redeeming shareholder
would normally incur brokerage expenses if he converted these securities to
cash.
 
                            MANAGEMENT OF THE FUND
                              THE VANGUARD GROUP
 
  Vanguard Convertible Securities Fund is a member of The Vanguard Group of
Investment Companies. Through their jointly-owned subsidiary, The Vanguard
Group, Inc. ("Vanguard"), the Fund and the other Funds in the Group obtain at
cost virtually all of their corporate management, administrative and distribu-
tion services. Vanguard also provides investment advisory services on an at-
cost basis to several of the Vanguard Funds. Vanguard employs a supporting
staff of management and administrative personnel needed to provide the requi-
site services to the Funds and also furnishes the Funds with necessary office
space, furnishings and equipment. Each Fund pays its share of Vanguard's total
expenses, which are allocated among the Funds under methods approved by the
Board of Directors (Trustees) of each Fund. In addition, each Fund bears its
own direct expenses such as legal, auditing and custodian fees.
 
  The Fund's Officers are also Officers and employees of Vanguard. No Officer
or employee owns, or is permitted to own, any securities of any external ad-
viser for the Funds.
 
  Vanguard adheres to a Code of Ethics established pursuant to Rule 17j-1 un-
der the Investment Company Act of 1940. The Code is designed to prevent unlaw-
ful practices in connection with the purchase or sale of securities by persons
associated with Vanguard. Under Vanguard's Code of Ethics, certain Officers
and employees of Vanguard who are considered access persons are permitted to
engage in personal securities transactions. However, such transactions are
subject to procedures and guidelines substantially similar to those recom-
mended by the mutual fund industry and approved by the U.S. Securities and Ex-
change Commission.
   
  Vanguard was established and operates under a Funds' Service Agreement which
was approved by the shareholders of each of the Funds. The amounts which each
of the Funds has invested in Vanguard are adjusted from time to time in order
to maintain the proportionate relationship between each Fund's relative net
assets and its contribution to Vanguard's capital. At November 30, 1997, the
Fund had contributed capital of $13,000 to Vanguard, representing .10% of Van-
guard's capitalization. The Funds' Service Agreement provides for the follow-
ing arrangement: (1) each Vanguard Fund may invest a maximum of 0.40% of its
assets in Vanguard; and (2) there is no restriction on the maximum aggregate
cash investment that the Vanguard Funds may make in Vanguard.     
 
                                                                            B-3
<PAGE>
 
MANAGEMENT
   
  Corporate management and administrative services include: (1) executive
staff; (2) accounting and financial; (3) legal and regulatory; (4) shareholder
account maintenance; (5) monitoring and control of custodian relationships;
(6) shareholder reporting; and (7) review and evaluation of advisory and other
services provided to the Funds by third parties. During the fiscal year ended
November 30, 1997, the Fund's share of actual net costs of operation relating
to management and administrative services provided by Vanguard totaled approx-
imately $434,000.     
 
DISTRIBUTION
 
  Vanguard provides all distribution and marketing activities for the Funds in
the Group. Vanguard Marketing Corporation, a wholly-owned subsidiary of Van-
guard, acts as Sales Agent for the shares of the Funds, in connection with any
sales made directly to investors in the states of Florida, Missouri, New York,
Ohio, Texas and such other states as it may be required.
 
  The principal distribution expenses are for advertising, promotional materi-
als and marketing personnel. Distribution services may also include organizing
and offering to the public, from time to time, one or more new investment com-
panies which will become members of the Group. The Directors and Officers of
Vanguard determine the amount to be spent annually on distribution activities,
the manner and amount to be spent on each Fund, and whether to organize new
investment companies.
   
  One-half of the distribution expenses of a marketing and promotional nature
is allocated among the Funds based upon relative net assets. The remaining
one-half of those expenses is allocated among the Funds based upon each Fund's
sales for the preceding 24 months relative to the total sales of the Funds as
a Group, provided, however, that no Fund's aggregate quarterly rate of contri-
bution for distribution expenses of a marketing and promotional nature shall
exceed 125% of average distribution expense rate for the Group, and that no
Fund shall incur annual distribution expenses in excess of .02 of 1% of its
average month-end net assets. During the fiscal year ended November 30, 1997,
the Fund paid approximately $34,000 of the group's distribution and marketing
expenses, or approximately 0.02% of 1% of its average month-end assets.     
 
INVESTMENT ADVISORY SERVICES
   
  Vanguard provides investment advisory services to Vanguard Money Market Re-
serves, Vanguard Bond Index Fund, Vanguard REIT Index Portfolio, Vanguard In-
dex Trust, Vanguard Balanced Index Fund, Vanguard International Equity Index
Fund, Vanguard Municipal Bond Fund, several portfolios of Vanguard Fixed In-
come Securities Fund, Vanguard Admiral Funds, Vanguard Institutional Index
Fund, several Portfolios of Vanguard Variable Insurance Fund, Vanguard Cali-
fornia Tax-Free Fund, Vanguard New York Tax-Free Fund, Vanguard Pennsylvania
Tax-Free Fund, Vanguard Ohio Tax-Free Fund, Vanguard Florida Insured Tax-Free
Fund, Vanguard New Jersey Tax-Free Fund, Vanguard Tax-Managed Fund, Aggressive
Growth Portfolio of Vanguard Horizon Fund, Total International Portfolio of
Vanguard STAR Fund, Vanguard Explorer Fund, a portion of Vanguard/Windsor II
and a portion of Vanguard/Morgan Growth Fund, as well as several indexed sepa-
rate accounts. These services are provided on an at-cost basis from a money
management staff employed directly by Vanguard. The compensation and other ex-
penses of this staff are paid by the Funds utilizing these services.     
 
B-4
<PAGE>
 
                            DIRECTORS AND OFFICERS
 
  The Officers of the Fund manage its day-to-day operations and are responsi-
ble to the Fund's Board of Directors. The Directors set broad policies for the
Fund and choose its Officers. The following is a list of Directors and Offi-
cers of the Fund and a statement of their present positions and principal oc-
cupations during the past five years. The mailing address of the Fund's Direc-
tors and Officers is Post Office Box 876, Valley Forge, PA 19482.

<TABLE>     
<S>                                       <C> 
JOHN C. BOGLE, (DOB: 5/8/1929)            ALFRED M. RANKIN, JR., (DOB:
Senior Chairman and Director*             10/8/1941) Director 
 Senior Chairman and Director of The       Chairman, President, Chief        
 Vanguard Group, Inc., and each of         Executive Officer, and Director of 
 the investment companies in The           NACCO Industries, Inc.; Director of
 Vanguard Group; Director of The           The BFGoodrich Company, and The    
 Mead Corporation, General Accident        Standard Products Company.         
 Insurance, and Chris-Craft                                                   
 Industries, Inc.                         JOHN C. SAWHILL, (DOB: 6/12/1936)   
                                          Director                            
JOHN J. BRENNAN, (DOB: 7/29/1954)          President and Chief Executive      
Chairman, Chief Executive Officer &        Officer of The Nature Conservancy;
Director*                                  formerly, Director and Senior     
 Chairman, Chief Executive Officer         Partner of McKinsey & Co., and    
 and Director of The Vanguard Group,       President of New York University;  
 Inc. and each of the investment           Director of Pacific Gas and        
 companies in The Vanguard Group.          Electric Company, Procter & Gamble 
                                           Company, and NACCO Industries.     
ROBERT E. CAWTHORN, (DOB: 9/28/1935)                                          
Director                                  JAMES O. WELCH, JR., (DOB:          
 Chairman Emeritus and Director of        5/13/1931) Director                 
 Rhone-Poulenc Rorer, Inc.; Managing       Retired Chairman of Nabisco Brands 
 Director of Global Health Care            Inc.; retired Vice Chairman and     
 Partners/DLJ Merchant Banking             Director of RJR Nabisco; Director   
 Partners; Director of Sun Company,        of TECO Energy, Inc., and Kmart     
 Inc., and Westinghouse Electric           Corporation.                        
 Corporation.                                                                  
                                          J. LAWRENCE WILSON, (DOB: 3/2/1936) 
BARBARA BARNES HAUPTFUHRER, (DOB:         Director                            
10/11/1928) Director                       Chairman and Chief Executive       
 Director of The Great Atlantic and        Officer of Rohm & Haas Company;    
 Pacific Tea Company, IKON Office          Director of Cummins Engine Company,
 Solutions, Inc., Raytheon Company,        and The Mead Corporation; and     
 Knight-Ridder, Inc., Massachusetts        Trustee of Vanderbilt University.  
 Mutual Life Insurance Co., and                                               
 Ladies Professional Golf                 RAYMOND J. KLAPINSKY, (DOB:         
 Association; and Trustee Emerita of      12/7/1938) Secretary*      
 Wellesley College.                        Managing Director and Secretary of
                                           The Vanguard Group, Inc.; Secretary
BRUCE K. MACLAURY, (DOB: 5/7/1931)         of each of the investment companies
Director                                   in The Vanguard Group.             
 President Emeritus of The Brookings                                          
 Institution; Director of American        RICHARD F. HYLAND, (DOB: 3/22/1937) 
 Express Bank, Ltd., The St. Paul         Treasurer*                         
 Companies, Inc., and National Steel       Treasurer of The Vanguard Group,  
 Corporation.                              Inc. and of each of the investment
                                           companies in The Vanguard Group.   
BURTON G. MALKIEL, (DOB: 8/28/1932)  
Director                                  KAREN E. WEST, (DOB: 9/13/1946)  
 Chemical Bank Chairman's Professor       Controller*                      
 of Economics, Princeton University;       Principal of The Vanguard Group,
 Director of Prudential Insurance          Inc.; Controller of each of the 
 Co. of America, Amdahl Corporation,       investment companies in The        
 Baker Fentress & Co., The Jeffrey         Vanguard Group.                    
 Co., and Southern New England                                                
 Telecommunications Company.                                                  
</TABLE>      
                                           -----------
                                           *Mr. Bogle and the Officers of the
                                           Fund are "interested persons" as
                                           defined in the Investment Company
                                           Act of 1940.
 
                                                                            B-5
<PAGE>
 
          
DIRECTOR/TRUSTEE COMPENSATION     
   
  The individuals in the table below serve as Directors/Trustees of all Van-
guard Funds, and each Fund pays a proportionate share of the
Directors'/Trustees' compensation. The Funds employ their officers on a shared
basis, as well. However, officers are compensated by The Vanguard Group, Inc.,
not the Funds.     
   
  INDEPENDENT DIRECTORS/TRUSTEES. The Funds compensate their independent
Directors/Trustees--that is, the ones who are not also officers of the Fund--
in three ways:     
   
 . The independent Directors/Trustees receive an annual fee for their service
  to the Funds, which is subject to reduction based on absences from scheduled
  Board meetings.     
   
 . The independent Directors/Trustees are reimbursed for the travel and other
  expenses that they incur attending Board meetings.     
   
 . Upon retirement, the independent Directors/Trustees receive an aggregate an-
  nual fee of $1,000 for each year served on the Board, up to fifteen years of
  service. This annual fee is paid for ten years following retirement, or un-
  til the Directors'/Trustees' death.     
   
  "INTERESTED" DIRECTORS/TRUSTEES. The Funds' interested Directors/Trustees--
Messrs. Bogle and Brennan--receive no compensation for their service in that
capacity. However, they are paid in their role as officers of The Vanguard
Group, Inc.     
   
  COMPENSATION TABLE. The following table provides compensation details for
each of the Directors. For the Fund, we list the amounts paid as compensation
and accrued as retirement benefits by the Fund for each Director. In addition,
the table shows the total amount of benefits that we expect each
Director/Trustee to receive from all Vanguard Funds upon retirement, and the
total amount of compensation paid to each Director/Trustee by all Vanguard
Funds. All information shown is for the fiscal year ended November 30, 1997.
    
                     VANGUARD CONVERTIBLE SECURITIES FUND
                              COMPENSATION TABLE
 
<TABLE>   
<CAPTION>
                          AGGREGATE   PENSION OR RETIREMENT    ESTIMATED      TOTAL COMPENSATION
                         COMPENSATION  BENEFITS ACCRUED AS  ANNUAL BENEFITS FROM ALL VANGUARD FUNDS
NAMES OF DIRECTORS        FROM FUND   PART OF FUND EXPENSES UPON RETIREMENT  PAID TO DIRECTORS(2)
- ------------------       ------------ --------------------- --------------- -----------------------
<S>                      <C>          <C>                   <C>             <C>
John C. Bogle(1)........     --                --                   --                  --
John J. Brennan(1)......     --                --                   --                  --
Barbara Barnes
 Hauptfuhrer............     $53               $ 8              $15,000             $70,000
Robert E. Cawthorn......     $53               $ 6              $13,000             $70,000
Bruce K. MacLaury.......     $58               $ 8              $12,000             $65,000
Burton G. Malkiel.......     $53               $ 5              $15,000             $70,000
Alfred M. Rankin, Jr....     $53               $ 4              $15,000             $70,000
John C. Sawhill.........     $53               $ 5              $15,000             $70,000
James O. Welch, Jr......     $53               $ 6              $15,000             $70,000
J. Lawrence Wilson......     $53               $ 4              $15,000             $70,000
</TABLE>    
- --------
(1) As "Interested Directors," Messrs. Bogle and Brennan receive no
    compensation for their service as Directors.
   
(2) The amounts reported in this column reflect the total compensation paid to
    each Director for their service as Director or Trustee of 35 Vanguard
    Funds (34 in the case of Mr. Malkiel; 28 in the case of Mr. MacLaury).
        
B-6
<PAGE>
 
                         INVESTMENT ADVISORY SERVICES
 
  The Fund employs Oaktree Capital Management, LLC (the "Adviser") under an
investment advisory agreement dated November 1, 1996 to manage the investment
and reinvestment of the assets of the Fund and to continuously review, super-
vise and administer the Fund's investment program. The Adviser discharges its
responsibilities subject to the control of the Officers and Directors of the
Fund.
 
  The Fund pays the Adviser an advisory fee at the end of each fiscal quarter,
calculated by applying a quarterly rate, based on the following annual per-
centage rates, to the Fund's average month-end net assets for the quarter (the
"Basic Fee"):
 
<TABLE>
<CAPTION>
   NET ASSETS                                                              RATE
   ----------                                                             ------
   <S>                                                                    <C>
   First $100 million.................................................... 0.425%
   Next $100 million..................................................... 0.400%
   Next $100 million..................................................... 0.375%
   Next $100 million..................................................... 0.350%
   Over $400 million..................................................... 0.325%
</TABLE>
 
  It is not intended that the funding under this contract will exceed $500
million.
 
  Beginning November 30, 1997, the Basic Fee payment to the Adviser may be in-
creased or decreased by a Performance Fee Adjustment (the "Adjustment"). The
Adjustment shall be a percentage of the Basic Fee and shall change proportion-
ately with the investment performance of the Fund relative to the investment
performance of the First Boston Convertible Securities Index (the "Index").
The following table sets forth the Adjustment of the Basic Fee payable by the
Fund to the Adviser under the investment advisory agreement.
 
<TABLE>
<CAPTION>
        CUMULATIVE PERFORMANCE OF
         THE FUND VS. THE INDEX          PERFORMANCE FEE ADJUSTMENT
         FOR THE RELEVANT PERIOD        AS A PERCENTAGE OF BASIC FEE
        -------------------------       ----------------------------
   <S>                                  <C>
   -100% of Performance Factor or more              -50%
   -1% to -99% of Performance Factor             0 to -50%
    0                                                0
   +1% to +99% Performance Factor                0 to +50%
   +100% of Performance Factor or more              +50%
</TABLE>
 
  The Adjustment will be calculated as follows, using data from the table be-
low:
 
  To calculate the Adjustment for a given quarter, (1) for the Relevant Period
for that quarter as set forth in the table below (the "Relevant Period"), the
difference between the investment performance of the Fund and the investment
performance of the Index (the "Performance Differential") will be calculated,
(2) the Performance Differential will be compared to the Performance Factor
specified by the table for that period to determine the extent to which an Ad-
justment is in order, and (3) the Adjustment will be the appropriate percent-
age of the Basic Fee* for an average quarter in that Relevant Period deter-
mined from the table above.
- --------
* For purposes of this calculation, the relevant Basic Fee is calculated by
  applying the quarterly rate against average assets over which performance is
  measured.
 
                                                                            B-7
<PAGE>
 
<TABLE>
<CAPTION>
                                                                    PERFORMANCE
   QUARTER ENDING                                 RELEVANT PERIOD  FACTOR (B.P.)
   --------------                                 ---------------- -------------
   <S>                                            <C>              <C>
   Before 11/30/97...............................       --no adjustment--
   11/30/97...................................... 12/1/96-11/30/97       67
    2/28/98...................................... 12/1/96-2/28/98        83
    5/31/98...................................... 12/1/96-5/31/98       100
    8/31/98...................................... 12/1/96-8/31/98       117
   11/30/98...................................... 12/1/96-11/30/98      133
    2/28/99...................................... 12/1/96-2/28/99       150
    5/31/99...................................... 12/1/96-5/31/99       167
    8/31/99...................................... 12/1/95-8/31/99       183
   11/30/99...................................... 12/1/96-11/30/99      200
   After 11/30/99................................ prior 36 months       200
</TABLE>
 
  The investment performance of the Fund for such period, expressed as a per-
centage of the net asset value per share of the Fund at the beginning of such
period, shall be the sum of: (i) the change in the net asset value per share
of the Fund during such period; (ii) the value of the cash distributions per
share of the Fund accumulated to the end of such period; and (iii) the value
of capital gains taxes per share paid or payable by the Fund on undistributed
realized long-term capital gains accumulated to the end of such period. For
this purpose, the value of distributions per share of realized capital gains,
of dividends per share paid from investment income and of capital gains taxes
per share paid or payable on undistributed realized long-term capital gains
shall be treated as reinvested in shares of the Fund at the net asset value
per share in effect at the close of business on the record date for the pay-
ment of such distributions and dividends and the date on which provision is
made for such taxes, after giving effect to such distributions, dividends and
taxes.
 
  The "investment record" of the Index for the period, expressed as a percent-
age of the Index level at the beginning of the period, shall be the sum of (i)
the change in the level of the Index during the period and (ii) the value,
computed consistently with the Index, of cash distributions having an ex-divi-
dend date occurring within the period made by companies whose securities com-
prise the Index.
   
  During the fiscal years ended November 30, 1995, 1996, and 1997, the Fund
paid investment advisory fees of approximately $674,000, $578,000 and $731,000
(before a decrease of $91,000 based on performance), respectively.     
 
  The agreement will continue until October 31, 1998 and will be renewable
thereafter for successive one-year periods, only if each renewal is specifi-
cally approved by a vote of the Fund's Board of Directors, including the af-
firmative votes of a majority of the Directors who are not parties to the con-
tract or "interested persons" (as defined in the Investment Company Act of
1940) of any such party, cast in person at a meeting called for the purpose of
considering such approval. In addition, the question of continuance of the
agreement may be presented to the shareholders of the Fund; in such event,
continuation must be approved by the affirmative vote of a majority of the
outstanding voting securities of the Fund. The agreement is automatically ter-
minated if assigned, and may be terminated without penalty at any time (1) ei-
ther by vote of the Board of Directors of the Fund or by vote of its outstand-
ing voting securities on 60 days' written notice to the Adviser, or (2) by the
Adviser upon 60 days' written notice to the Fund.
 
  The Fund's Board of Directors may, without the approval of shareholders,
provide for:
 
    A. The employment of a new investment adviser pursuant to the terms of a
  new advisory agreement, either as a replacement for an existing adviser or
  as an additional adviser;
 
    B. A change in the terms of an advisory agreement; and
 
B-8
<PAGE>
 
    C. The continued employment of an existing adviser, on the same advisory
  contract terms, where a contract has been assigned because of a change in
  control of the adviser.
 
  Any such change will only be made upon not less than 30 days' prior written
notice to shareholders, which shall include the information concerning the ad-
viser that would have normally been included in a proxy statement.
 
  Oaktree Capital Management, LLC specializes in selected niche investment
markets. The founders of Oaktree formed the company in April of 1995 after
having managed funds in the convertible securities, distressed debt, and high
yield bond areas of Trust Company of the West (TCW) since 1985.
   
  Larry W. Keele, Principal and one of the five founders of Oaktree, serves as
Portfolio Manager of the Fund. Mr. Keele is supported by research and other
investment services provided by the professional staff of Oaktree. As of No-
vember 30, 1997, Oaktree managed approximately $9.7 billion.     
 
                            PORTFOLIO TRANSACTIONS
 
  The investment advisory agreement authorizes the Adviser (with the approval
of the Fund's Board of Directors) to select the brokers or dealers that will
execute the purchases and sales of portfolio securities for the Fund and di-
rects the Adviser to use its best efforts to obtain the best available price
and most favorable execution as to all transactions for the Fund. The Adviser
has undertaken to execute each investment transaction at a price and commis-
sion which provides the most favorable total cost or proceeds reasonably ob-
tainable under the circumstances.
 
  In placing portfolio transactions, the Adviser will use its best judgment to
choose the broker most capable of providing the brokerage services necessary
to obtain best available price and most favorable execution. The full range
and quality of brokerage services available will be considered in making these
determinations. In those instances where it is reasonably determined that more
than one broker can offer the brokerage services needed to obtain the best
available price and most favorable execution, consideration may be given to
those brokers which supply investment research and statistical information and
provide other services in addition to execution services to the Fund and/or
the Adviser. The Adviser considers such information useful in the performance
of its obligations under the agreement, but is unable to determine the amount
by which such services may reduce its expenses.
 
  The investment advisory agreement also incorporates the concepts of Section
28(e) of the Securities Exchange Act of 1934 by providing that, subject to the
approval of the Fund's Board of Directors, the Adviser may cause the Fund to
pay a broker-dealer which furnishes brokerage and research services a higher
commission than that which might be charged by another broker-dealer for ef-
fecting the same transaction; provided that such commission is deemed reason-
able in terms of either that particular transaction or the overall responsi-
bilities of the Adviser to the Fund.
 
  Currently, it is the Fund's policy that the Adviser may at times pay higher
commissions in recognition of brokerage services felt necessary for the
achievement of better execution of certain securities transactions that other-
wise might not be available. The Adviser will only pay such higher commissions
if it believes this to be in the best interest of the Fund. Some brokers or
dealers who may receive such higher commissions in recognition of brokerage
services related to execution of securities transactions are also providers of
research information to the Adviser and/or the Fund. However, the Adviser has
informed the Fund that it will not pay higher commission rates specifically
for the purpose of obtaining research services.
 
  Since the Fund does not market its shares through intermediary brokers or
dealers, it is not the Fund's practice to allocate brokerage or principal
business on the basis of sales of its shares which may be through such firms.
However, the Fund may place portfolio orders with qualified broker-dealers who
 
                                                                            B-9
<PAGE>
 
recommend the Fund to other clients, or who act as agent in the purchase of
the Fund's shares for their clients, and may, when a number of brokers and
dealers can provide comparable best price and execution on a particular trans-
action, consider the sale of the Fund shares by a broker or dealer in select-
ing among qualified broker-dealers.
   
  Some securities considered for investment by the Fund may also be appropri-
ate for other clients served by the Adviser. If purchase or sale of securities
consistent with the investment policies of the Fund and one or more of these
other clients serviced by the Adviser are considered at or about the same
time, transactions in such securities will be allocated among the Fund and
such other clients in a manner deemed equitable by the Adviser. During the
fiscal years ended November 30, 1995, 1996 and 1997 the Fund paid $38,822,
$111,718, and $41,776 in brokerage commissions.     
 
                              GENERAL INFORMATION
                    DESCRIPTION OF SHARES AND VOTING RIGHTS
 
  The Fund is a diversified open-ended investment company established under
Maryland law. The Fund's Amended and Restated Articles of Incorporation dated
April 8, 1986 permit the Directors to issue 1,000,000,000 shares of common
stock, with a $.001 par value. The Board of Directors has the power to desig-
nate one or more classes ("Portfolios") of shares of common stock and to clas-
sify or reclassify any unissued shares with respect to such Portfolios. Cur-
rently the Fund is offering shares of one portfolio.
 
  The shares of the Fund are fully paid and non-assessable, and have no pref-
erence as to conversion, exchange, dividends, retirement or other features.
The shares have no pre-emptive rights. The shares have non-cumulative voting
rights, which means that the holders of more than 50% of the shares voting for
the election of Directors can elect 100% of the Directors if they choose to do
so. A shareholder is entitled to one vote for each full share held (and a
fractional vote for each fractional share held), then standing in his name on
the books of the Fund. On any matter submitted to a vote of shareholders, all
shares of the Fund then issued and outstanding and entitled to vote, irrespec-
tive of the class, shall be voted in the aggregate and not by class except (i)
when required by the Investment Company Act of 1940, shares shall be voted by
individual class, and (ii) when the matter does not affect any interest of a
particular class, then only shareholders of the affected class or classes
shall be entitled to vote thereon.
 
                            YIELD AND TOTAL RETURN
   
  The yield of the Fund for the 30-day period ended November 30, 1997 was
+4.33%.     
   
  The average annual total return of the Fund for the one-, five-, and ten-
year periods ended November 30, 1997 was +14.81%, +10.96% and +13.06%, respec-
tively. The average annual total return of the Fund for the period since its
inception on June 17, 1986 was +9.74%.     
 
                              COMPARATIVE INDEXES
 
  Vanguard may use reprinted material discussing The Vanguard Group, Inc. or
any of the member funds of the Vanguard Group of Investment Companies.
 
  Each of the investment company members of the Vanguard Group, including Van-
guard Convertible Securities Fund, may, from time to time, use one or more of
the following unmanaged indices for comparative performance purposes.
 
  STANDARD AND POOR'S 500 COMPOSITE STOCK PRICE INDEX--is a well diversified
list of 500 companies representing the U.S. Stock Market.
 
B-10
<PAGE>
 
   
  STANDARD & POOR'S MIDCAP 400 INDEX--is composed of 400 medium sized domestic
stocks.     
   
  STANDARD & POOR'S/BARRA 600 VALUE INDEX--contains stocks of the S&P SmallCap
600 Index which have a lower than average price-to-book ratio.     
   
  STANDARD & POOR'S/BARRA 600 GROWTH INDEX--contains stocks of the S&P
SmallCap 600 Index which have a higher than average price-to-book ratio.     
   
  RUSSELL 1000 VALUE INDEX--consists of the stocks in the Russell 1000 Index
(comprising the 1,000 largest U.S.-based companies measured by total market
capitalization) with the lowest price-to-book ratios, comprising 50% of the
market capitalization of the Russell 1000.     
 
  WILSHIRE 5000 EQUITY INDEX--consists of more than 7,000 common equity secu-
rities, covering all stocks in the U.S. for which daily pricing is available.
 
  WILSHIRE 4500 EQUITY INDEX--consists of all stocks in the Wilshire 5000 ex-
cept for the 500 stocks in the Standard and Poor's 500 Index.
   
  MORGAN STANLEY CAPITAL INTERNATIONAL EAFE INDEX--is an arithmetic, market
value-weighted average of the performance of over 900 securities listed on the
stock exchanges of countries in Europe, Australia, Asia, and the Far East.
    
  GOLDMAN SACHS 100 CONVERTIBLE BOND INDEX--currently includes 71 bonds and 29
preferreds. The original list of names was generated by screening for convert-
ible issues of $100 million or greater in market capitalization. The index is
priced monthly.
 
  SALOMON BROTHERS GNMA INDEX--includes pools of mortgages originated by pri-
vate lenders and guaranteed by the mortgage pools of the Government National
Mortgage Association.
 
  SALOMON BROTHERS HIGH-GRADE CORPORATE BOND INDEX--consists of publicly is-
sued, non-convertible corporate bonds rated Aa or Aaa. It is a value-weighted,
total return index, including approximately 800 issues with maturities of 12
years or greater.
 
  THE LEHMAN AGGREGATE BOND INDEX is composed of the Lehman Brothers
Government/Corporate Bond Index and the Lehman Brothers Mortgage-Backed Secu-
rities Index and includes treasury issues, agency issues, corporate bond is-
sues and mortgage-backed securities. All securities are rated investment grade
or higher by Moody's Investors Service, Standard & Poor's Corporation, or
Fitch Investor's Service, in that order. All issues have at least one year to
maturity and an outstanding par value of at least $100 million.
 
  LEHMAN LONG-TERM TREASURY BOND INDEX--is composed of all bonds covered by
the Shearson Lehman Hutton Treasury Bond Index with maturities of 10 years or
greater.
 
  MERRILL LYNCH CORPORATE & GOVERNMENT BOND INDEX--consist of over 4,500 U.S.
Treasury, agency and investment grade corporate bonds.
 
  LEHMAN CORPORATE (BAA) BOND INDEX--all publicly offered fixed-rate, noncon-
vertible domestic corporate bonds rated Baa by Moody's, with a maturity longer
than 1 year and with more than $25 million outstanding. This index includes
over 1,000 issues.
 
  LEHMAN BROTHERS LONG-TERM CORPORATE BOND INDEX--is a subset of the Lehman
Corporate Bond Index covering all corporate, publicly issued, fixed-rate, non-
convertible U.S. debt issues rated at least Baa, with at least $50 million
principal outstanding and maturity greater than 10 years.
 
 
                                                                           B-11
<PAGE>
 
  BOND BUYER MUNICIPAL BOND INDEX--is a yield index on current-coupon high
grade general-obligation municipal bonds.
 
  STANDARD & POOR'S PREFERRED INDEX--is a yield index based upon the average
yield of four high grade, noncallable preferred stock issues.
 
  NASDAQ INDUSTRIAL INDEX--is composed of more than 3,000 industrial issues.
It is a value-weighted index calculated on price change only and does not in-
clude income.
 
  COMPOSITE INDEX--70% Standard & Poor's 500 Index and 30% NASDAQ Industrial
Index.
 
  COMPOSITE INDEX--65% Standard & Poor's 500 Index and 35% Lehman Long-Term
Corporate AA or Better Bond Index.
   
  COMPOSITE INDEX--65% Lehman Long-Term Corporate AA or Better Bond Index and
a 35% weighting in a blended equity composite (75% Standard & Poor's/BARRA
Value Index, 12.5% Standard & Poor's Utilities Index and 12.5% Standard &
Poor's Telephone Index).     
   
  LEHMAN LONG-TERM CORPORATE AA OR BETTER BOND INDEX--consists of all publicly
issued, fixed rate, nonconvertible investment grade, dollar-denominated, SEC-
registered corporate debt rated AA or AAA.     
 
  LEHMAN BROTHERS AGGREGATE BOND INDEX--is a market weighted index that con-
tains over 4,000 individually priced U.S. Treasury, agency, corporate, and
mortgage pass-through securities corporate rated Baa--or better. The Index has
a market value of approximately $4 trillion.
   
  LEHMAN BROTHERS MUTUAL FUND SHORT (1-5) GOVERNMENT/CORPORATE INDEX--is a
market weighted index that contains individually priced U.S. Treasury, agency,
and corporate investment grade bonds rated BBB--or better with maturities be-
tween 1 and 5 years. The index has a market value of approximately $1.6 tril-
lion.     
   
  LEHMAN BROTHERS MUTUAL FUND INTERMEDIATE (5-10) GOVERNMENT/CORPORATE INDEX--
is a market weighted index that contains individually priced U.S. Treasury,
agency, and corporate securities rated BBB--or better with maturities between
5 and 10 years. The index has a market value of approximately $700 billion.
       
  LEHMAN BROTHERS LONG (10+) GOVERNMENT/CORPORATE INDEX--is a market weighted
index that contains individually priced U.S. Treasury, agency, and corporate
securities rated BBB--or better with maturities of ten or more years. The in-
dex has a market value of over $900 billion.     
 
  LEHMAN BROTHERS MUTUAL FUND SHORT (1-5) INVESTMENT GRADE DEBT INDEX--is a
market weighted index that contains all investment grade corporate debt secu-
rities with maturities of one to five years. The index has a market value of
approximately $175 billion.
 
  LEHMAN BROTHERS MUTUAL FUND SHORT (1-5) U.S. TREASURY INDEX--is a market
weighted index that contains all U.S. Treasury securities with maturities of
one to five years. The index has a market value of approximately $1.1 tril-
lion.
 
  LEHMAN BROTHERS MUTUAL FUND SHORT (1-5) U.S. GOVERNMENT INDEX--is a market
weighted index that contains all U.S. Government agency and Treasury securi-
ties with maturities of one to five years. The index has a market value of ap-
proximately $1.3 trillion.
 
  LEHMAN BROTHERS MUTUAL FUND INTERMEDIATE (5-10) U.S. TREASURY INDEX--is a
market weighted index that contains all U.S. Treasury securities with maturi-
ties of five to ten years. The index has a market value of approximately $300
billion.
 
 
B-12
<PAGE>
 
  LEHMAN BROTHERS MUTUAL FUND INTERMEDIATE (5-10) INVESTMENT GRADE DEBT IN-
DEX--is a market weighted index that contains all investment grade debt secu-
rities with maturities of five to ten years. The index has a market value of
approximately $225 billion.
 
  LIPPER SMALL COMPANY GROWTH FUND AVERAGE--the average performance of small
company growth funds as defined by Lipper Analytical Services, Inc. Lipper de-
fines a small company growth fund as a fund that by prospectus or portfolio
practice, limits its investments to companies on the basis of the size of the
company. From time to time, Vanguard may advertise using the average perfor-
mance and/or the average expense ratio of the small company growth funds.
(This fund category was first established in 1982. For years prior to 1982,
the results of the Lipper Small Company Growth category were estimated using
the returns of the Funds that constituted the Group at its inception).
 
  LIPPER GENERAL EQUITY FUND AVERAGE--an industry benchmark of average general
equity funds with similar investment objectives and policies, as measured by
Lipper Analytical Services, Inc.
 
  LIPPER FIXED INCOME FUND AVERAGE--an industry benchmark of average fixed in-
come funds with similar investment objectives and policies, as measured by
Lipper Analytical Services, Inc.
 
  RUSSELL 3000 INDEX--consists of approximately the 3,000 largest stocks of
U.S.-domiciled companies commonly traded on the New York and American Stock
Exchanges or the NASDAQ over-the-counter market, accounting for over 90% of
the market value of publicly traded stocks in the U.S.
 
  RUSSELL 2000 STOCK INDEX--consists of the smallest 2,000 stocks within the
Russell 3000; a widely used benchmark for small capitalization common stocks.
 
  LIPPER BALANCED FUND AVERAGE--an industry benchmark of average balanced
funds with similar investment objectives and policies, as measured by Lipper
Analytical Services, Inc.
 
  LIPPER NON-GOVERNMENT MONEY MARKET FUND AVERAGE--an industry benchmark of
average non-government money market funds with similar investment objectives
and policies, as measured by Lipper Analytical Services, Inc.
 
  LIPPER GOVERNMENT MONEY MARKET FUND AVERAGE--an industry benchmark of aver-
age government money market funds with similar investment objectives and poli-
cies, as measured by Lipper Analytical Services, Inc.
 
  FIRST BOSTON CONVERTIBLE SECURITIES INDEX--Established as a performance
benchmark in 1982, the Index is valued monthly and generally includes 250 to
300 issues of convertible securities rated B- or better by Standard & Poor's,
and a predominant proportion of the market capitalization of the total value
of all convertible securities.
 
                             FINANCIAL STATEMENTS
   
  The Fund's Financial Statements for the year ended November 30, 1997, in-
cluding the financial highlights for each of the five fiscal years in the pe-
riod ended November 30, 1997, appearing in the Fund's 1997 Annual Report to
Shareholders, and the report thereon of Price Waterhouse LLP, independent ac-
countants, also appearing therein, are incorporated by reference in this
Statement of Additional Information. The Fund's 1997 Annual Report to Share-
holders is enclosed with this Statement of Additional Information.     
 
                                                                           B-13
<PAGE>
 
                APPENDIX--DESCRIPTION OF SECURITIES AND RATINGS
 
I. DESCRIPTION OF BOND RATINGS
 
  Excerpts from Moody's Investors Service, Inc., ("Moody's") description of
its four highest bond ratings: AAA--judged to be the best quality. They carry
the smallest degree of investment risk; AA--judged to be of high quality by
all standards. Together with the Aaa group they comprise what are generally
known as high grade bonds; A--possess many favorable investment attributes and
are to be considered as "upper medium grade obligations"; BAA--considered as
medium grade obligations, i.e., they are neither highly protected nor poorly
secured. Interest payments and principal security appear adequate for the
present but certain protective elements may be lacking or may be characteris-
tically unreliable over any great length of time. BA--judged to have specula-
tive elements; their future cannot be considered as well assured; B--generally
lack characteristics of the desirable investment; CAA--are of poor standing.
Such issues may be in default or there may be present elements of danger with
respect to principal or interest; CA--speculative in a high degree; often in
default; C--lowest rated class of bonds; regarded as having extremely poor
prospects.
 
  Moody's also supplies numerical indicators 1, 2 and 3 to rating categories.
The modifier 1 indicates that the security is in the higher end of its rating
category; the modifier 2 indicates a mid-range ranking; and 3 indicates a
ranking toward the lower end of the category.
 
  Excerpts from Standard & Poor's Corporation ("S&P") description of its five
highest bond ratings: AAA--highest grade obligations. Capacity to pay interest
and repay principal is extremely strong; AA--also qualify as high grade obli-
gations. A very strong capacity to pay interest and repay principal and dif-
fers from AAA issues only in small degree; A--regarded as upper medium grade.
They have a strong capacity to pay interest and repay principal although they
are somewhat susceptible to the adverse effects of changes in circumstances
and economic conditions than debt in higher rated categories; BBB--regarded as
having an adequate capacity to pay interest and repay principal. Whereas it
normally exhibits adequate protection parameters, adverse economic conditions
or changing circumstances are more likely to lead to a weakened capacity to
pay interest and repay principal for debt in this category than in higher
rated categories. This group is the lowest which qualifies for commercial bank
investment. BB, B, CCC, CC--predominately speculative with respect to capacity
to pay interest and repay principal in accordance with terms of the obliga-
tion; BB indicates the lowest degree of speculation and CC the highest.
 
  S&P applies indicators "+," no character, and "-" to its rating categories.
The indicators show relative standing within the major rating categories.
 
B-14
<PAGE>
 
                                    PART C
 
                  VANGUARD CONVERTIBLE SECURITIES FUND, INC.
 
                               OTHER INFORMATION
 
ITEM 24. FINANCIAL STATEMENTS AND EXHIBITS
 
  (A) FINANCIAL STATEMENTS
   
  The Registrant's audited financial statements for the year ended November
30, 1997, including Price Waterhouse LLP's report thereon, are incorporated by
reference in the Statement of Additional Information from the Registrant's
1997 Annual Report, which has been filed with the Commission. The financial
statements included in the Annual Report are:     
     
   1. Statement of Net Assets as of November 30, 1997.     
     
   2. Statement of Operations for the year ended November 30, 1997.     
     
   3. Statement of Changes in Net Assets for the years ended November 30,
      1996 and November 30, 1997.     
     
   4. Financial Highlights for each of the five years ended November 30,
      1997.     
   5. Notes to Financial Statements.
   6. Report of Independent Accountants.
 
  (B) EXHIBITS
 
   1. Articles of Incorporation
   2. By-Laws of Registrant
   3. Not Applicable
   4. Not Applicable
   5. Not Applicable
   6. Not Applicable
   7. Reference is made to the section entitled "Management of the Fund" in
      the Registrant's Statement of Additional Information
   8. Form of Custody Agreement
   9. Form of Vanguard Service Agreement
  10. Opinion of Counsel
  11. Consent of Independent Accountants*
  12. Financial Statements--reference is made to (a) above
  13. Not Applicable
  14. Not Applicable
  15. Not Applicable
  16. Schedule for Computation of Performance Quotations*
  27. Financial Data Schedule
- --------
*Filed herewith.
 
ITEM 25. PERSONS CONTROLLED BY OR UNDER COMMON CONTROL WITH REGISTRANT
 
  Registrant is not controlled by or under common control with any person. The
Officers of the Registrant, the investment companies in The Vanguard Group of
Investment Companies and The Vanguard Group, Inc. are identical. Reference is
made to the caption "Management of the Fund" in the Prospectus constituting
Part A and "Management of the Fund" in the Statement of Additional Information
constituting Part B of this Registration Statement.
 
ITEM 26. NUMBER OF HOLDERS OF SECURITIES
   
  As of November 30, 1997 there were 9,658 shareholders.     
 
                                                                            C-1
<PAGE>
 
ITEM 27. INDEMNIFICATION
   
  Reference is made to Article XI of Registrant's Articles of Incorporation.
Insofar as indemnification for liability arising under the Securities Act of
1933 may be permitted to Directors, Officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the Securities and Exchange Commission
such indemnification is against public policy as expressed in the Act and is,
therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the Registrant of expenses
incurred or paid by a Director, Officer or controlling person of the Regis-
trant in the successful defense of any action, suit or proceeding) is asserted
by such Director, Officer or controlling person in connection with the securi-
ties being registered, the Registrant will, unless in the opinion of its coun-
sel the matter has been settled by controlling precedent, submit to a court of
appropriate jurisdiction the question whether such indemnification by it is
against public policy as expressed in the Act and will be governed by the fi-
nal adjudication of such issue.     
 
ITEM 28. BUSINESS AND OTHER CONNECTIONS OF INVESTMENT ADVISER
 
  Oaktree Capital Management LLC. ("Oaktree"), 550 South Hope Street, 22nd
Floor, Los Angeles, California 90071, is the Investment Adviser.
 
ITEM 29. PRINCIPAL UNDERWRITERS
 
  (a) None
 
  (b) Not Applicable
 
ITEM 30. LOCATION OF ACCOUNTS AND RECORDS
 
  The books, accounts and other documents required by Section 31(a) under the
Investment Company Act of 1940 and the rules promulgated thereunder will be
maintained in the physical possession of Registrant; Registrant's Transfer
Agent, The Vanguard Group, Inc. c/o The Vanguard Financial Center, Valley
Forge, Pennsylvania 19482; and the Registrant's Custodian, Morgan Guaranty
Trust Company of New York.
 
ITEM 31. MANAGEMENT SERVICES
 
  Other than the Amended and Restated Funds' Service Agreement with The Van-
guard Group, Inc. which was previously filed as Exhibit 9(c) and described in
Part B hereof under "Management of the Fund," the Registrant is not a party to
any management-related service contract.
 
ITEM 32. UNDERTAKINGS
       
  Registrant hereby undertakes to provide an Annual Report to Shareholders to
prospective investors, free of charge, upon request.
 
C-2
<PAGE>
 
                                  SIGNATURES
   
  PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933 AND THE INVEST-
MENT COMPANY ACT OF 1940, THE REGISTRANT HEREBY CERTIFIES THAT IT MEETS THE
REQUIREMENTS FOR EFFECTIVENESS OF THIS REGISTRATION STATEMENT PURSUANT TO RULE
485(B) UNDER THE SECURITIES ACT OF 1933 AND HAS DULY CAUSED THIS POST-EFFEC-
TIVE AMENDMENT TO THIS REGISTRATION STATEMENT TO BE SIGNED ON ITS BEHALF BY
THE UNDERSIGNED, THEREUNTO DULY AUTHORIZED, IN THE TOWN OF VALLEY FORGE AND
THE COMMONWEALTH OF PENNSYLVANIA, ON THIS 6TH DAY OF MARCH, 1998.     
 
                                          Vanguard Convertible Securities
                                           Fund, Inc.
 
                                              
                                          By:           (signature)
                                              -----------------------------   
                                                  (RAYMOND J. KLAPINSKY)
                                                     JOHN J. BRENNAN*,
                                                  
                                               CHAIRMAN AND CHIEF EXECUTIVE
                                                       OFFICER     
 
  PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, THIS POST-EFFEC-
TIVE AMENDMENT TO THE REGISTRATION STATEMENT HAS BEEN SIGNED BELOW BY THE FOL-
LOWING PERSONS IN THE CAPACITIES AND ON THE DATE INDICATED:


<TABLE>     
<CAPTION> 

 
             SIGNATURES                    TITLE                 DATE
             ----------                    -----                 ----
<S>                                 <C>                      <C> 
By:          (signature)            Senior Chairman of   
    ---------------------------         the Board and         March 6, 1998
       (RAYMOND J. KLAPINSKY)           Director                      
           JOHN C. BOGLE*                                
 
             
By:          (signature)            Chairman, Chief            
    ---------------------------         Executive Officer     March 6, 1998
       (RAYMOND J. KLAPINSKY)           and Director                  
          JOHN J. BRENNAN*                                
 
                              
By:          (signature)               Director               March 6, 1998
    ---------------------------
       (RAYMOND J. KLAPINSKY)                                         
         ROBERT E. CAWTHORN*
 
                              
By:          (signature)               Director  
   ----------------------------                               March 6, 1998
       (RAYMOND J. KLAPINSKY)                    
       BARBARA B. HAUPTFUHRER*
 
                                           
By:          (signature)               Director               March 6, 1998
   ---------------------------- 
       (RAYMOND J. KLAPINSKY)                                         
       BRUCE K. MACLAURY, JR.*
 
                          
By:          (signature)               Director               March 6, 1998
   ----------------------------
       (RAYMOND J. KLAPINSKY)                                         
         BURTON G. MALKIEL*
 
             
By:          (signature)               Director                  
    ---------------------------                               March 6, 1998
       (RAYMOND J. KLAPINSKY)                                         
       ALFRED M. RANKIN, JR.*
 
                             
By:          (signature)               Director               March 6, 1998
   ----------------------------
       (RAYMOND J. KLAPINSKY)                                         
          JOHN C. SAWHILL*
 
             
By:          (signature)               Director               March 6, 1998
   ----------------------------
       (RAYMOND J. KLAPINSKY)                                         
        JAMES O. WELCH, JR.*
 
           
By:          (signature)               Director               March 6, 1998
   ---------------------------- 
       (RAYMOND J. KLAPINSKY)                                         
         J. LAWRENCE WILSON*
 
                                                                 
By:          (signature)               Treasurer and          March 6, 1998
   ----------------------------         Principal Financial  
       (RAYMOND J. KLAPINSKY)           and Accounting                
         RICHARD F. HYLAND*             Officer
 
</TABLE>      

* By Power of Attorney. See File Number 2-14336, January 23, 1990. Incorpo-
rated by Reference.
<PAGE>
 
                               INDEX TO EXHIBITS
 
<TABLE>
<S>                                                                    <C>
Consent of Independent Accountants.................................... EX-99.B11
Schedule for Computation.............................................. EX-99.B16
Financial Data Schedule...............................................     EX-27
</TABLE>

<PAGE>
 
                                                                      EX-99.B11
 
                      CONSENT OF INDEPENDENT ACCOUNTANTS
   
  We hereby consent to the incorporation by reference in the Prospectus and
Statement of Additional Information constituting parts of this Post-Effective
Amendment No. 17 to the registration statement on Form N-1A (the "Registration
Statement") of our report dated December 31, 1997 relating to the financial
statements and financial highlights appearing in the November 30, 1997 Annual
Report to Shareholders of Vanguard Convertible Securities Fund, Inc., which
are also incorporated by reference into the Registration Statement. We also
consent to the references to us under the headings "Financial Highlights" and
"General Information" in the Prospectus and under the heading "Financial
Statements" in the Statement of Additional Information.     
 
Price Waterhouse LLP
Philadelphia, PA
   
March 5, 1998     

<PAGE>
 
                                                                       EX-99.B16
 
              SCHEDULE FOR COMPUTATION OF PERFORMANCE QUOTATIONS
                          CONVERTIBLE SECURITIES FUND
   
1. AVERAGE ANNUAL TOTAL RETURN (As of November 30, 1997)     
 
    P (1 + T)/n/ = ERV
 
  Where:              P = a hypothetical initial payment of $1,000
 
                      T = average annual total return
 
                      N = number of years
 
                    ERV = ending redeemable value at the end of the period
    
EXAMPLE:
- --------

ONE YEAR
- --------
   P   =   $1,000   
   T   =   +14.81%  
   N   =   1        
 ERV   =   $1,148.07 

 FIVE YEARS
 ----------
   P   =   $1,000   
   T   =   +10.96%  
   N   =   5        
 ERV   =   $1,682.14 

 TEN YEARS
 ---------
   P   =   $1,000   
   T   =   +13.06%  
   N   =   10       
 ERV   =   $3,412.68      

- --------
   
2. YIELD (30 Days Ended November 30, 1997)     
 
                a-b
    Yield = 2[(----- + 1 )/6/ - 1]
               c X d
 
  Where:      a = dividends and interest paid during the period
 
              b = expense dollars during the period (net of reimbursements)
 
              c = the average daily number of shares outstanding during the
                  period
 
              d = the maximum offering price per share on the last day of the
                  period
    
  Example     a = $685,918.69      
    
              b = $8,780.05      
    
              c = 14,548,580.425      
                      
              d = $13.01      
                  
     
          Yield = 4.33%      

<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 6
<CIK> 0000791107
<NAME> VANGUARD CONVERTIBLE SECURITIES FUND, INC.
<MULTIPLIER> 1,000
<CURRENCY> US
       
<S>                             <C>
<PERIOD-TYPE>                   YEAR
<FISCAL-YEAR-END>                          NOV-30-1997
<PERIOD-START>                             DEC-01-1996
<PERIOD-END>                               NOV-30-1997
<EXCHANGE-RATE>                                      1
<INVESTMENTS-AT-COST>                          187,799
<INVESTMENTS-AT-VALUE>                         192,825
<RECEIVABLES>                                    4,724
<ASSETS-OTHER>                                      13
<OTHER-ITEMS-ASSETS>                                 0
<TOTAL-ASSETS>                                 197,562
<PAYABLE-FOR-SECURITIES>                         3,740
<SENIOR-LONG-TERM-DEBT>                              0
<OTHER-ITEMS-LIABILITIES>                        4,718
<TOTAL-LIABILITIES>                              8,458
<SENIOR-EQUITY>                                      0
<PAID-IN-CAPITAL-COMMON>                       165,762
<SHARES-COMMON-STOCK>                           14,532
<SHARES-COMMON-PRIOR>                           12,988
<ACCUMULATED-NII-CURRENT>                        2,102
<OVERDISTRIBUTION-NII>                               0
<ACCUMULATED-NET-GAINS>                         16,214
<OVERDISTRIBUTION-GAINS>                             0
<ACCUM-APPREC-OR-DEPREC>                         5,026
<NET-ASSETS>                                   189,104
<DIVIDEND-INCOME>                                2,279
<INTEREST-INCOME>                                6,394
<OTHER-INCOME>                                       0
<EXPENSES-NET>                                   1,153
<NET-INVESTMENT-INCOME>                          7,520
<REALIZED-GAINS-CURRENT>                        16,197
<APPREC-INCREASE-CURRENT>                          169
<NET-CHANGE-FROM-OPS>                           23,886
<EQUALIZATION>                                       0
<DISTRIBUTIONS-OF-INCOME>                        6,451
<DISTRIBUTIONS-OF-GAINS>                        16,736
<DISTRIBUTIONS-OTHER>                                0
<NUMBER-OF-SHARES-SOLD>                          3,549
<NUMBER-OF-SHARES-REDEEMED>                      3,766
<SHARES-REINVESTED>                              1,761
<NET-CHANGE-IN-ASSETS>                          19,380
<ACCUMULATED-NII-PRIOR>                          1,033
<ACCUMULATED-GAINS-PRIOR>                       16,753
<OVERDISTRIB-NII-PRIOR>                              0
<OVERDIST-NET-GAINS-PRIOR>                           0
<GROSS-ADVISORY-FEES>                              640
<INTEREST-EXPENSE>                                   0
<GROSS-EXPENSE>                                  1,183
<AVERAGE-NET-ASSETS>                           175,505
<PER-SHARE-NAV-BEGIN>                            13.07
<PER-SHARE-NII>                                   0.53
<PER-SHARE-GAIN-APPREC>                           1.17
<PER-SHARE-DIVIDEND>                              0.47
<PER-SHARE-DISTRIBUTIONS>                         1.29
<RETURNS-OF-CAPITAL>                                 0
<PER-SHARE-NAV-END>                              13.01
<EXPENSE-RATIO>                                   0.67
<AVG-DEBT-OUTSTANDING>                               0
<AVG-DEBT-PER-SHARE>                                 0
        

</TABLE>


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