Shares of Apellis Pharmaceuticals Inc. /zigman2/quotes/202103251/composite APLS +0.51% plunged 31.6% toward a 10-month low to pace all premarket losers Friday, after one of the Phase 3 studies of the biopharmaceutical company's eye disease treatment failed to meet its primary endpoint. The company said late Thursday that the OAKS study for pegcetacoplan met the primary endpoint, as it significantly reduced geographic atrophy (GA) lesion growth, while the DERBY study missed its primary endpoint of GA lesion growth reduction. The company said it plans to submit a New Drug Application (NDA) for pegcetacoplan for GA to the U.S. Food and Drug Administration in the first half of 2022. Wedbush downgraded Apellis to neutral from outperform, saying the previous upgraded was predicated on both studies holding a "high probability of success," but the readout ended up in the "mixed bag" scenario. J.P. Morgan slashed its stock price target to $57 from $101, but kept its overweight rating, saying "patience required" but pegcetacoplan "likely gets across the goal line" eventually. Apellis' stock has shed 2.8% year to date through Thursday, while the iShares Biotechnology ETF /zigman2/quotes/206189322/composite IBB +0.33% has advanced 14.8% and the S&P 500 /zigman2/quotes/210599714/realtime SPX +1.42% has gained 19.6%.