<PAGE> 1
Filed Pursuant to Rule 424(b)(3)
Registration No. 333-24557
PROSPECTUS SUPPLEMENT
DATED OCTOBER 8, 1998
(To Prospectus dated June 29, 1998, as amended by Prospectus Supplement dated
August 24, 1998)
ADAPTEC, INC.
U.S. $230,000,000
4 3/4% Convertible Subordinated Notes due February 1, 2004
and
Shares of Common Stock Issuable Upon Conversion Thereof
-----------------------
This Prospectus Supplement together, with the Prospectus and Prospectus
Supplements listed above, is to be used by certain holders of the
above-referenced securities or by their transferees, pledgees, donees or their
successors in connection with the offer and sale of the above referenced
securities.
<PAGE> 2
SELLING SECURITYHOLDERS
The table captioned "Selling Securityholders" commencing on page 24 of the
Prospectus is hereby amended to reflect the following additions and changes.
<TABLE>
<CAPTION>
NUMBER OF SHARES OF
PRINCIPAL AMOUNT OF NOTES COMMON STOCK BENEFICIALLY
BENEFICIALLY OWNED OWNED AND OFFERED
SELLING SECURITYHOLDER AND OFFERED HEREBY HEREBY (1)(2)
- ----------------------------------------------------------------- ------------------------- -------------------------
<S> <C> <C>
Goldman Sachs & Company.......................................... 300,000 5,807
</TABLE>
(1) Includes shares of Common Stock issuable upon conversion of the Notes.
(2) Assumes a conversion price of $51.66 per share, and a cash payment in lieu
of any fractional share interest; such conversion price is subject to
adjustment as described under "Description of Notes -- Conversion."
Accordingly the number of shares of Common Stock issuable upon conversion
of the Notes may increase or decrease from time to time. Under the terms of
Indenture, fractional shares will not be issued upon conversion of the
Notes; cash will be paid in lieu of fractional shares, if any.
