Dyax Corp. (NASDAQ: DYAX) today announced that it is offering to sell shares of its common stock in a proposed underwritten public offering. All shares to be sold in the offering are being sold by Dyax. The offering is subject to market and other conditions and there can be no assurance as to whether or when the offering may be completed or as to the actual size or terms of the offering. Jefferies LLC is acting as the sole book-running manager with Cowen and Company, LLC, Leerink Swann LLC and Needham & Company, LLC acting as co-managers for the offering. A registration statement relating to the shares of Dyax common stock being offered has been filed with, and declared effective by, the Securities and Exchange Commission (the “SEC”). A preliminary prospectus supplement relating to the offering has also been filed with the SEC and is available on the SEC’s website at http://www.sec.gov. Before you invest, you should read the base prospectus contained in such registration statement, the preliminary prospectus supplement and the documents incorporated by reference for more complete information about Dyax and this offering. Copies of the preliminary prospectus supplement and the base prospectus may be obtained by sending a request to: Jefferies LLC, Attention: Equity Syndicate Prospectus Department, 520 Madison Avenue, 12 th Floor, New York, NY, 10022, by telephone at 877-547-6340 or by email at Prospectus_Department@Jefferies.com. This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of, these securities in any state or other jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such state or jurisdiction. About Dyax Dyax is a fully integrated biopharmaceutical company focused on the discovery, development and commercialization of novel biotherapeutics for unmet medical needs. The Company's key value drivers are the KALBITOR ® (ecallantide) business, DX-2930 and the Licensing and Funded Research Program (LFRP). For additional information about Dyax, please visit www.dyax.com. For additional information about KALBITOR, including full prescribing information, please visit www.KALBITOR.com. Disclaimer This press release contains forward-looking statements, including statements regarding Dyax’s proposed offering of common stock, that involve a number of risks and uncertainties. Statements that are not historical facts are based on Dyax’s current expectations, beliefs and assumptions regarding the market for its common stock. There can be no assurance regarding the completion, timing or size of the proposed offering. Important factors that could cause actual outcomes to differ materially from those indicated by these forward-looking statements include risks and uncertainties related to market conditions, the satisfaction of customary closing conditions related to the proposed public offering and others described in Dyax’s most recent Annual Report on Form 10-K for the year ended December 31, 2012. Dyax cautions investors not to place undue reliance on the forward-looking statements contained in this release. These statements speak only as of the date of this release, and Dyax undertakes no obligations to update or revise these statements, except as may be required by law.