Chiron Announces Amended Merger Agreement with Novartis; Novartis to Acquire All Outstanding Chiron Shares for $48.00 Per Share

Chiron Corporation (Nasdaq:CHIR) today announced that
it has entered into an amendment to its previously announced merger
agreement with Novartis providing for Novartis to increase to $48.00
per Chiron share the price it will pay for the approximately 56
percent of Chiron shares that Novartis does not already own. The
amended merger agreement has been unanimously approved by Chiron's
non-Novartis directors.
   The merger will now require a majority of outstanding shares as of
the record date to be voted in favor of the transaction. Both CAM
North America and ValueAct Capital have informed Chiron and Novartis
that they and their affiliated entities intend to vote in favor of the
transaction, subject to the fiduciary and legal obligations applicable
to them.
   Chiron today also announced that it has reached an agreement in
principle to settle all claims in the previously reported stockholder
actions challenging the proposed transaction with Novartis. The
proposed settlement is subject to court approval following notice to
the class and a hearing.
   Chiron will promptly send updated proxy materials to shareholders
and plans to convene the special shareholders meeting as scheduled on
April 12, 2006, and to immediately adjourn the meeting and then
reconvene on April 19, 2006. As all necessary regulatory approvals
were previously received, Chiron expects the merger to close promptly
after the stockholder vote on April 19, 2006.

   About Chiron

   Chiron delivers innovative and valuable products to protect human
health by advancing pioneering science across the landscape of
biotechnology. The company works to deliver on the limitless promise
of science and make a positive difference in people's lives. For more
information about Chiron, please visit www.chiron.com.