<PAGE> 1
PROSPECTUS SUPPLEMENT NO. 5 FILED PURSUANT TO RULE 424(b)(3)
TO PROSPECTUS DATED DECEMBER 10, 1998 REGISTRATION NO. 333-63439
$86,250,000
ASPEN TECHNOLOGY, INC.
5 1/4% CONVERTIBLE SUBORDINATED DEBENTURES DUE JUNE 15, 2005
This Prospectus Supplement supplements the information we provided in our
December 10, 1998 Prospectus relating to our 5 1/4% Convertible Subordinated
Debentures due June 15, 2005 and the shares of our common stock that we must
issue upon conversion of those Debentures, and in our Prospectus Supplements No.
1, No. 2, No. 3 and No. 4. This Prospectus Supplement is not complete without
the supplemented Prospectus, and we have not authorized anyone to deliver or use
this Prospectus Supplement without the supplemented Prospectus.
In this Prospectus Supplement, we use capitalized terms that we defined in
the Prospectus. You should read the Prospectus to understand those terms. Unless
we indicate otherwise, the information in this Prospectus Supplement is as of
June 4, 1999.
We are providing this Prospectus Supplement to update the following
information to the table in the Prospectus under the caption "Selling
Securityholders":
<TABLE>
<CAPTION>
PRINCIPAL AMOUNT OF SHARES OF COMMON SHARES OF COMMON
DEBENTURES BENEFICIALLY STOCK BENEFICIALLY STOCK BENEFICIALLY
OWNED PRIOR TO THE OWNED PRIOR TO THE SHARES OF OWNED AFTER THE
OFFERING AMOUNT OF OFFERING COMMON OFFERING
------------------ DEBENTURES -------------------- STOCK -------------------
SELLING SECURITYHOLDER NUMBER PERCENT(1) OFFERED(2) NUMBER(3) PERCENT(4) OFFERED(3) NUMBER PERCENT(4)
---------------------- ------ ---------- ---------- --------- ---------- ---------- ------ ----------
<S> <C> <C> <C> <C> <C> <C> <C> <C>
Putnam Convertible Income-
Growth Trust................ $4,691,000 5.4% $4,691,000 88,561 * 88,561 -- --
c/o Putnam Investment
Management, Inc.
7 Shattuck Road, C-8-A
Andover, MA 01810
Putnam High Income Convertible
and Bond Fund.............. 1,500,000 1.7 1,500,000 28,318 * 28,318 -- --
</TABLE>
- ------------
* Less than one percent.
(1) For purposes of this Prospectus Supplement only, we have calculated this
percentage on the basis of $86,250,000 aggregate principal amount of
Debentures outstanding on June 4, 1999.
(2) This Selling Securityholder has indicated that it may offer all of the
Debentures that it owns. As a result, no Debentures will be owned after the
offering.
(3) For purposes of this Prospectus Supplement only, we have calculated this
number using the conversion rate described on the front cover page of the
Prospectus.
(4) For purposes of this Prospectus Supplement only, we have calculated this
percentage on the basis of 24,944,760 shares of common stock outstanding on
June 4, 1999.
THE DATE OF THIS PROSPECTUS SUPPLEMENT IS JUNE 7, 1999.
