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.
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.