Stocks ended the day mixed as biotechs took a hard stumble Wednesday. CSX (CSX) topped estimates late in the day, while Humana (HUM) and Cigna (CI) fell in heavy volume during the regular session on Medicare ratings. Amazon (AMZN) launched a new music streaming service Wednesday. Extraction Oil & Gas (XOG) rose 15% on its first day of trading. Tomorrow, watch for Delta Air Lines (DAL) and Taiwan Semiconductor (TSM) earnings results, plus the release of Sony's (SNE) PlayStation VR.