Dyax Corp. (NASDAQ: DYAX) today announced that the underwriters of its previously announced public offering have exercised in full their option to purchase an additional 1,384,615 shares of the Company’s common stock at a price to the public of $6.50 per share, less customary underwriting discounts and commissions. The net proceeds of approximately $8.5 million from the exercise of the option brings the aggregate net proceeds from the offering to approximately $64.7 million, after deducting the underwriting discount and other estimated offering expenses payable by Dyax. The additional shares were delivered to the underwriters on October 18, 2013. Jefferies LLC acted as the sole book-running manager and Cowen and Company, LLC, Leerink Swann LLC and Needham & Company, LLC acted as the co-managers for the offering. As previously announced, Dyax intends to use the net proceeds from this offering to fund research and development activities, including the development of DX-2930, a therapeutic candidate for the prophylactic treatment of hereditary angioedema (HAE), and for general corporate purposes. 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 final prospectus supplement relating to the offering has been filed with the SEC and is available on the SEC’s website at http://www.sec.gov. Copies of the final prospectus supplement and related prospectus may be obtained from Jefferies LLC, Attention: Syndicate Prospectus Department, 520 Madison Avenue, 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.