Infinity Pharmaceuticals (INFI)

2. Net Loss Per Share

Basic and diluted net loss per share is presented in conformity with Statement of Financial Accounting Standard No. 128, “Earnings per Share” (FAS 128). In accordance with FAS 128, basic net loss per share has been computed by dividing net loss by the weighted average number of shares of common stock outstanding during the period, less shares subject to repurchase. In loss periods, common stock equivalents are excluded from the computation of diluted net loss per

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share as their effect would be anti-dilutive. The total number of shares issuable upon exercise of stock options and rights to acquire restricted stock excluded from the calculation of diluted earnings per share since they are anti-dilutive was 2,008,408 and 2,175,446 for the three and six months ended June 30, 2006, respectively and 3,678,847 and 3,661,725 for the three and six months ended June 30, 2005, respectively.

2. Net Loss Per Share

Basic and diluted net loss per share is presented in conformity with Statement of Financial Accounting Standard No. 128, “Earnings per Share” (FAS 128). In accordance with FAS 128, basic net loss per share has been computed by dividing net loss by the weighted average number of shares of common stock outstanding during the period, less shares subject to repurchase. In loss periods, common stock equivalents are excluded from the computation of diluted net loss per share as their effect would be anti-dilutive. The total number of shares issuable upon exercise of stock options and rights to acquire restricted stock excluded from the calculation of diluted earnings per share since they are anti-dilutive were 2,692,680 and 3,506,466 for the three months ended March 31, 2006 and 2005, respectively.

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