Shares of Melinta Therapeutics Inc. /zigman2/quotes/201002965/composite MLNT -4.78% more than doubled (up 128%) on heavy volume Wednesday, after the antibiotics developer said its supplemental new drug application (sNDA) for Baxdela was accepted by the U.S. Food and Drug Administration. Trading volume spiked to over 4.7 million shares, compared with the full-day average of about 334,000 shares through Tuesday, and enough to make the stock the most actively traded ahead of the open. The company said the FDA has granted "priority review" status for Baxdela, in which the sNDA seeks to expand the current indication to include adult patients with community-acquired bacterial pneumonia (CABP). "BAXDELA's potency and activity against the most common bacterial pathogens seen in CABP indicate it could play a significant role in the treatment of this life-threatening illness, if approved," said Melinta Chief Medical Officer Sue Cammarata. "We look forward to working with the FDA to help evaluate bringing this potential option to people with CABP as soon as possible." The stock has tumbled 50% year to date through Tuesday, while the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.28% has gained 16%.