Vertex proposes public offering of six million common shares

Vertex intends to grant the underwriters an over-allotment option to purchase up to an additional 900,000 shares of its common stock. Concurrently with the offering of its common stock, Vertex also intends to offer, subject to market and other conditions, $250 million aggregate principal amount of convertible senior subordinated notes due 2013 in an underwritten public offering under a separate automatically effective shelf registration statement on file with the Securities and Exchange Commission.

Vertex also expects to grant the underwriters an over-allotment option to purchase up to $37.5 million aggregate principal amount of additional notes on the same terms and conditions. The common stock offering and the note offering are being conducted as separate public offerings, and the offerings are not contingent upon each other. The price of the common stock and the interest rate, conversion price, and other terms of the notes will be determined by negotiations between Vertex and the underwriters upon the pricing of the offerings.