US STOCKS-Biotech among biggest Nasdaq gainers
* Indexes up: Dow 1 pct, S&P 0.9 pct, Nasdaq 0.9 pct
By Ryan Vlastelica
NEW YORK, Sept 26 (Reuters) - Biotech stocks were among the biggest percentage gainers on the Nasdaq on Friday, though the benchmark index only posted mild gains on the day.
Agios Pharmaceuticals (NasdaqGS: AGIO - news) surged 20 percent to $64.02 on its heaviest one-day volume since its initial public offering last year. Earlier, the company said it would present clinical data from an ongoing phase I study.
Among other big gainers, Repros Therapeutics (NasdaqCM: RPRX - news) climbed 18 percent to $10.59 after reporting the trial results for its secondary hypogonadism treatment. Esperion Therapeutics (Stuttgart: 0ET.SG - news) was up 16 percent at $20.95. Both stocks moved on volume that was much heavier than average.
Despite the gains, the Nasdaq Biotech index was up a more moderate 0.3 percent. The index was pressured as AcelRx plummeted 19 percent to $5.44 after saying it was looking to resubmit the new drug application for its Zalviso product in the first quarter of 2015.
Index snapshot at 14:20 EDT:
* S&P 500 was rising 16.96 points, or 0.86 percent.
* Nasdaq Comp was gaining 40.11 points, or 0.9 percent.
* Dow industrials was adding 171.56 points, or 1.01 percent.
* Russell 2000 was adding 6.75 points, or 0.61 percent.
* S&P MidCap was adding 8.78 points, or 0.64 percent.
* S&P SmallCap was gaining 2.99 points, or 0.47 percent. (Editing by Nick Zieminski)