EXHIBIT 11.1 TRIANGLE PHARMACEUTICALS, INC. (A DEVELOPMENT STAGE COMPANY) COMPUTATION OF NET LOSS PER SHARE AND PRO FORMA NET LOSS PER SHARE (UNAUDITED) THREE MONTHS NINE MONTHS THREE MONTHS NINE MONTHS ENDED ENDED ENDED ENDED SEPTEMBER 30, SEPTEMBER 30, SEPTEMBER 30, SEPTEMBER 30, ------------- ------------- ------------- ------------- 1996 (1) 1996 (1) 1997 (2) 1997 (2) ------------- ------------- ------------- ------------- Historical weighted average shares........................... 19,988,451 18,554,524 Pro forma historical weighted average shares outstanding........ 4,107,643 4,925,945 -- -- Series A preferred stock, convertible to Common Stock at consummation of the initial public offering.................. 5,231,671 5,231,671 -- -- Series B preferred stock, convertible to Common Stock at consummation of the initial public offering.................. 3,706,234 3,706,234 -- -- Common stock equivalents for preferred stock warrants outstanding...................... -- -- -- -- Common stock equivalents for options outstanding.............. -- -- -- -- ----------- ----------- ------------ ------------ Shares used in computing pro forma net loss per share......... 13,045,548 13,863,850 19,988,451 18,554,524 ----------- ----------- ------------ ------------ ----------- ----------- ------------ ------------ Net Loss.......................... $(2,538,859) $(8,038,277) $(18,214,006) $(27,374,905) ----------- ----------- ------------ ------------ ----------- ----------- ------------ ------------ Pro forma net loss per share...... $ (0.19) $ (0.58) $ (0.91) $ (1.48) ----------- ----------- ------------ ------------ ----------- ----------- ------------ ------------ (1) Weighted average common stock outstanding during the period including all common stock issued at prices below the public offering price during the twelve month period preceding the offering as if it was outstanding at inception (July 12, 1995). Issuance of convertible preferred stock, preferred stock warrants and common stock options at prices below the public offering price during the twelve month period preceding the offering have been included as common stock equivalent as if they had been issued as common stock as of July 12, 1995. (2) The weighted average shares outstanding used in the calculation of net loss per share do not include common stock equivalents because they have the effect of reducing net loss per share.