Wall Street secured gains again by late afternoon Wednesday in unpredictable trading following President-elect Donald Trump's first press conference since July. The Volatility Index, otherwise known as the fear index, spiked earlier in the session. Biotech companies and drugmakers were broadly lower after Trump suggested he would aggressively negotiate the price the U.S. pays for drugs. Stocks including Allergan (AGN) , Mylan (MYL) , Perrigo (PRGO) , Valeant (VRX) and Bristol-Myers Squibb (BMY) slumped after Trump's late-morning presser. Workday (WDAY) climbed after Walmart (WMT) signed up for a subscription, a deal that will likely cover the highest number of workers in the company's history. The world's largest retailer has more than two million employees worldwide. Volkswagen (VLKAY) rose after securing a plea deal with U.S. regulators worth $4.3 billion. The case covered the automaker's highly-publicized emissions-rigging scandal.