Shares of exercise bike company Peloton are under pressure from a scathing research report. The selling comes on the heels of blowback from the company’s widely mocked ad. Andrew Left of Citron Research is well known on Wall Street for targeting companies he thinks have flawed business models. He places bets that their stocks will fall. And he’s now taking aim at Peloton Interactive Inc. The stock took a hit last week after Peloton aired an ad in which a husband gifts one of its stationary bikes to his wife for the holidays. Critics called the ad sexist and tone deaf.