<PAGE>
As filed with the Securities and Exchange Commission on August 23, 2000
AMENDMENT NO. 1
TO
SCHEDULE TO
TENDER OFFER STATEMENT
UNDER SECTION 14(d)(1) OR 13(e)(1)
OF THE SECURITIES EXCHANGE ACT OF 1934
PATHOGENESIS CORPORATION
(Name of Subject Company)
CHIRON CORPORATION AND
PICARD ACQUISITION CORP.
A WHOLLY OWNED SUBSIDIARY OF
CHIRON CORPORATION
(Names of Filing Persons)
COMMON STOCK,
AND THE ASSOCIATED PREFERRED STOCK PURCHASE RIGHTS
(Title of Class of Securities)
70321E104
(CUSIP Number of Class of Securities)
WILLIAM G. GREEN, ESQ.
SENIOR VICE PRESIDENT, GENERAL COUNSEL AND SECRETARY
CHIRON CORPORATION
4560 HORTON STREET
EMERYVILLE, CA 94608
(510) 655-8750
(Name, address, and telephone numbers of person
authorized to receive notices and communications on
behalf of filing persons)
with copies to:
ALISON S. RESSLER, ESQ.
MATTHEW G. HURD, ESQ.
C/O SULLIVAN & CROMWELL
1888 CENTURY PARK EAST
LOS ANGELES, CALIFORNIA 90067-1725
(310) 712-6600
[ ] Check the box if the filing relates solely to preliminary communications
made before the commencement of a tender offer.
Check the appropriate boxes below to designate any transactions to which the
statement relates:
[x] third-party tender offer subject to Rule 14d-1.
[ ] issuer tender offer subject to Rule 13e-4.
<PAGE>
[ ] going-private transaction subject to Rule 13e-3.
[ ] amendment to Schedule 13D under Rule 13d-2.
Check the following box if the filing is a final amendment reporting the
results of the tender offer: [ ]
This Amendment No. 1 amends and supplements the Tender Offer
Statement on Schedule TO, dated August 21, 2000, relating to the offer by
Picard Acquisition Corp. ("Merger Sub"), a Delaware Corporation and a wholly
owned subsidiary of Chiron Corporation, a Delaware corporation ("Parent"), to
purchase all of the outstanding shares of common stock, par value $0.001 per
share (the "Common Stock"), of PathoGenesis Corporation, a Delaware
corporation (the "Company"), together with the associated rights to purchase
Series A Junior Preferred Stock (the "Rights") issued pursuant to the Rights
Agreement, dated as of June 26, 1997, as amended, between the Company and
Harris Trust and Savings Bank (the Common Stock and the Rights together being
referred to herein as the "Shares"), at a price of $38.50 per Share, net to
the seller in cash, upon the terms and subject to the conditions set forth in
the Offer to Purchase, dated August 21, 2000 (the "Offer to Purchase"), a
copy of which was attached as Exhibit (a)(1) to Schedule TO, and in the
related Letter of Transmittal, a copy of which was attached thereto as
Exhibit (a)(2).
ITEMS 1-11.
Not Applicable
ITEM 12. EXHIBITS.
Item 12 is hereby amended to add the following:
<TABLE>
<S> <C>
(a)(10) Material distributed to PathoGenesis employees on
August 23, 2000 entitled, "Employee Questions and
Answers Regarding Employee Stock Purchase Plan
(ESPP) and 401K Plan" and "Employee Questions and
Answers Regarding PathoGenesis Employee Stock
Options".
</TABLE>
--------------
<PAGE>
ITEM 13. INFORMATION REQUIRED BY SCHEDULE 13E-3
Not Applicable.
SIGNATURE
After due inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.
Date: August 23, 2000
PICARD ACQUISITION CORP.
/s/ William G. Green
--------------------------
Name: William G. Green
Title: Director, Vice
President and Secretary
CHIRON CORPORATION
/s/ William G. Green
--------------------------
Name: William G. Green
Title: Senior Vice President,
Secretary and General
Counsel
