CHIR Chiron (MM)

Chiron Corporation (Nasdaq:CHIR) today announced that Schering AG has provided formal notice to Chiron of its intention to exercise its option under its collaboration agreement with Chiron to purchase or lease all assets used by Chiron in the manufacture for Schering of BETASERON(R) interferon beta-1b products and all contractual rights at their fair market or lease value. The purchase/lease option, as stipulated in a change-in-control clause in the agreement, is subject to the closing of the proposed acquisition of Chiron by Novartis AG. The agreement requires that the value be determined by an independent third party mutually agreed upon by both parties. The collaboration agreement between Chiron and Schering is set to expire in October 2008. 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. This news release contains forward-looking statements, including statements regarding the sale or lease of assets to Schering and the proposed acquisition of Chiron by Novartis AG, that involve risks and uncertainties and are subject to change. Forward-looking statements often address our expected future performance and often contain words such as "expects," "anticipates," "intends," "plans," "believes," "seeks" or "will." A discussion of the company's operations and financial condition, including factors that may affect its business and future prospects that could cause actual results and developments to differ materially from those expressed or implied by forward-looking statements, is contained in documents the company has filed with the SEC, including the Form 10-K for the year ended December 31, 2004, and the Form 10-Q for the quarter ended September 30, 2005, and will be contained in all subsequent periodic filings made with the SEC. These documents identify important factors that could cause the company's actual performance to differ from current expectations, including, among others, regulatory review and approvals, manufacturing capabilities, intellectual property protections and defenses, litigation, and marketing effectiveness. No assurance can be given as to whether or not Schering will purchase or lease the assets described in this press release or that the transactions contemplated by the merger agreement with Novartis AG will be consummated. Chiron does not undertake an obligation to update the forward-looking information the company is giving today. NOTE: BETASERON is a trademark of Schering AG.