<PAGE>
SUPPLEMENT TO PROSPECTUS FOR
NORTH AMERICAN SENIOR FLOATING RATE FUND, INC.
Dated April 13, 1999
Effective March 1, 2000, the expense limitations with respect to the
Distribution Fees paid on Class B and Class C shares are being revised
resulting in an increase in Total Fund Operating Expenses. Pages 3 and 4 of
the Prospectus are therefore replaced in their entirety by the attached pages.
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FUND EXPENSES
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The following table and Example are intended to help you understand the
direct and indirect expenses applicable to each class of shares of the Fund.
<TABLE>
<CAPTION>
SHAREHOLDER TRANSACTION EXPENSES Class B Class C
- -------------------------------------------------------------------------------
<S> <C> <C>
Sales Charge Imposed on Purchases None None
of Shares (as a percentage of
offering price)
Sales Charge Imposed on Dividend
Reinvestment None None
Early Withdrawal Charges 3% first year 1% first year
(as a percentage of original purchase
price 2.5% second year 0% after first year
or repurchase price, whichever is
lower) 2% third year
1% fourth year
0% after fourth year
Exchange fee None None
<CAPTION>
ANNUAL FUND OPERATING EXPENSES
(as a percentage of average net assets attributable to
common shares)(1)
Class B Class C
- -------------------------------------------------------------------------------
<S> <C> <C>
Management Fee(2) 0.85% 0.85%
Interest Payments on Borrowed Funds 0.00% 0.00%
Service Fee 0.25% 0.25%
Distribution Fee (after
reimbursement)(3)(4) 0.10% 0.20%
Administration Fee (after
reimbursement)(2)(4) 0.00% 0.00%
Other Expenses 0.25% 0.25%
----- -----
Total Fund Operating Expenses (after
reimbursement)(4) 1.45% 1.55%
</TABLE>
(1) See "Management of the Fund" for additional information.
(2) The management fee and administration fee are based on a percentage of the
Fund's average daily gross assets (gross assets are total assets minus all
liabilities except debt).
(3) The Fund pays a distribution fee of 0.50% of average daily net assets for
both Class B and Class C shares.
(4) The Fund's investment adviser has agreed to reimburse the Fund's expenses
to the extent necessary so that total annualized Fund expenses do not
exceed 1.45% and 1.55% of average daily gross assets for Class B Shares
and Class C Shares, respectively (gross assets are total assets minus all
liabilities except debt). Absent such reimbursement, estimated expenses
would be: management fee of 0.85%, interest payments on borrowed funds of
0.00%, administration fee of 0.40%, service fee of 0.25%, distribution fee
of 0.50%, and other expenses of 0.25%; and total Fund operating expenses
of 2.25%. This agreement may be terminated by CAM on thirty (30) days'
written notice.
The Fund also has Class A Shares, which are not offered to the public. Class B
Shares automatically convert into Class A Shares eight years after purchase.
Class C Shares purchased on or after August 13, 1999 do not
<PAGE>
have an automatic conversion feature; Class C Shares purchased before August
13, 1999 automatically convert into Class A Shares ten years after purchase.
See "Multiple Pricing System--Conversion Feature." Class A Shares are not
subject to any shareholder transaction expenses. The estimated annual Fund
operating expenses of Class A Shares are: management fee of 0.85%, interest
payments on borrowed funds of 0.00%, administration fee of 0.40%, service fee
of up to 0.25%, and other expenses of 2.00%, with total annual expenses of
1.45%. This reflects reimbursement of the 0.40% administration fee and a
portion of other expenses pursuant to CAM's agreement to reimburse the Fund's
expenses to the extent necessary so that total annualized Fund expenses do not
exceed 1.45% of average daily gross assets. See note 4, above. Absent this
reimbursement, total Fund operating expenses of Class A shares would be 3.50%.
Service and distribution fees include an asset-based sales charge; as a result
long-term shareholders of the Fund may pay more than the economic equivalent
of the maximum front-end sales charges permitted by the National Association
of Securities Dealers, Inc. ("NASD"). See "How to Buy Fund Shares."
EXAMPLE
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An investor would pay the following expenses on a $1,000 investment, assuming
a 5% annual return.
<TABLE>
<CAPTION>
1 YEAR 3 YEARS 5 YEARS 10 YEARS
------ ------- ------- --------
<S> <C> <C> <C> <C>
Class B Shares.................................. $45 $66 $79 $174
Class C Shares.................................. $26 $49 $84 $185
</TABLE>
Federal regulations require the Example to assume a 5% annual return, but
actual return will vary. The Example assumes reinvestment of all dividends and
distributions at net asset value and repurchase at the end of each period. The
Example assumes that the fee waivers and reimbursements referred to under
"Fund Expenses" are in effect.
The Example should not be considered a representation of future expenses
because future expenses may be greater or less than those shown.
Actual expenses may be higher or lower than the amounts shown in the fee
table and, consequently, the actual expenses incurred by an investor may be
greater (in the event the expense limitations are removed) or less than the
amounts shown in the Example. Moreover, while the Example assumes a 5% annual
return, performance will vary and may result in a return greater or less than
5%.
The paragraph entitled Automatic Conversion on Page 6 is replaced in its
entirety with the following:
Automatic Conversion. The Fund also has Class A Shares, which are not
offered to the public. Class B shares will automatically convert to
Class A Shares of the Fund eight years after purchase. Class C Shares
purchased on or after August 13, 1999 do not have an automatic
conversion feature; Class C shares purchased before August 13, 1999
will automatically convert to Class A Shares of the Fund ten years
after purchase. Class A Shares are subject to a service fee of up to
0.25% of average annual net assets. See "Multiple Pricing System--
Conversion Feature."
The fourth paragraph on the section entitled Advisory Arrangements on Page
18 is replaced in its entirety with the following:
CAM has agreed to waive a portion of its advisory fee or reimburse
the Fund in order to prevent the total expenses of the Fund, excluding
taxes, portfolio brokerage commissions, interest, certain litigation
and indemnification expenses, and extraordinary expenses, from
exceeding 1.45% of average daily gross assets for Class B Shares and
1.55% of average daily gross assets for Class C Shares. This agreement
may be terminated by CAM at any time on thirty (30) days' written
notice.
2
<PAGE>
The last paragraph on Page 21 in the section entitled Factors for
Consideration is replaced in its entirety with the following:
There are important distinctions among the classes of shares that you
should understand and evaluate in comparing the options offered by the
Multiple Pricing System. Class C shares are subject to the same ongoing
distribution and service fees as Class B shares but, as a result of
current fee waivers and reimbursements, Class B distribution fees are
0.10% while Class C distribution fees are 0.20%, Class B Shares thus
pay correspondingly higher dividends per share, Class C Shares are
subject to a lower Early Withdrawal Charge and an Early Withdrawal
Charge for a shorter period of time (one year as opposed to three
years) than Class B shares. Class B shares convert to Class A shares in
eight years whereas Class C shares upon purchase do not have a
conversion feature. Class A shares are not subject to the distribution
fee applicable to Class B and Class C shares, and, accordingly, may pay
correspondingly higher dividends per share. However, as long as the
current fee waivers and reimbursements are in effect, Class A and Class
B Shares may have the same aggregate expense ratios.
0100:90531 JANUARY 26, 2000
3
