Check out the companies making headlines after the bell Wednesday:
Chimerix stock jumped in after-hours trading after asset-management company Point72, which was founded by Steve Cohen, disclosed a 5.3 percent stake in the small-cap biotech. Chimerix lost about 80 percent of its value on Monday after its phase three trial of an antiviral drug failed. The drug being tested was one that combats an infection called cytomegalovirus.
Shares of Weight Watchers edged up in extended-hours trading. The stock soared 19 percent during the regular session after the weight loss company launched an advertising campaign starring Oprah Winfrey. Winfrey bought a 10 percent stake in the company, about 6.4 million shares, in October.