Exhibit 11.1 Computation of net loss per share and unaudited pro forma net loss per share Period from inception Year ended Nine months ended (May 5, 1995) December 31, September 30, through -------------------------- ----------------------------- December 31, 1995 1996 1997 1997 1998 ----------------- ---- ---- ---- ---- (in thousands, except per share data) Basic and diluted net loss per share: Net loss $ (188) $(1,698) $(7,425) $(4,548) $(7,988) ======= ======= ======= ======= ======= Basic and diluted weighted average common shares outstanding 2,200 1,743 1,687 1,584 2,813 ======= ======= ======= ======= ======= Basic and diluted net loss per share $ (0.09) $ (0.97) $ (4.40) $ (2.87) $ (2.84) ======= ======= ======= ======= ======= Year ended Nine months December 31, ended September 30, 1997 1998 ------------ ------------------- (in thousands, except per share data) Unaudited pro forma basic and diluted net loss per share: Net loss $(7,425) $(7,988) ======= ======= Unaudited pro forma basic and diluted weighted average shares outstanding: Shares attributable to common stock (1) 2,515 3,237 Shares attributable to the assumed conversion of Preferred Stock upon closing of an initial public offering 2,863 3,817 ------- ------- Unaudited pro forma basic and diluted weighted average shares 5,378 7,054 ======= ======= Unaudited pro forma basic and diluted net loss per share $ (1.38) $ (1.13) ======= ======= (1) Includes outstanding common stock subject to repurchase under a stock restriction agreement which lapses upon the consummation of the Offering.