In brief: Facebook might be relieved to hear it isn’t the only site getting lambasted right now. Twitter’s shares plummeted after a short-seller said it “has become the Harvey Weinstein of social media”—a response to an Amnesty International report that examined the abuse of women on the microblogging site. Investor Andrew Left's Citron Research wrote that Twitter had now become “uninvestable.”

Earlier this week, human rights advocacy group Amnesty International, in collaboration with Element AI, published the findings of its Troll Report project: the world’s largest crowd-sourced dataset of online abuse against women. It analyzed millions of tweets received by 778 journalists and politicians in the UK and US using machine learning, and found that 7.1 percent were “problematic” or “abusive.” That amounts to 1.1 million tweets across the year, or one every 30 seconds. Women of color were 34 percent more likely to be targeted, and black women were 84 percent more likely than white women to be mentioned in problematic tweets.

“Citron has been following Twitter for years and when we read the just-published piece from Amnesty International, we immediately knew the stock had become uninvestable and advertisers will soon be forced to take a hard look at all sponsorships with Twitter,” the Citron report said.

Twitter told Amnesty its study was unclear on how it defined and identified “problematic” content. “Context matters when evaluating abusive behavior and determining appropriate enforcement actions,” wrote Twitter’s legal, policy and trust and safety global lead Vijaya Gadde.

The Harvey Weinstein comparison contributed to Twitter shares falling as much as 13 percent to $28.51. Citron set a new share price target of $20 for the company; in August, it had set a price of $52.

While Twitter’s stock has declined around 7.4 percent this month—more than Facebook’s—it is still up about 21.7 percent this year.