On an already rough day on Wall Street, Twitter’s stock plunged more than most, falling 11% after a Wall Street research firm tagged it “the Harvey Weinstein of social media.”

Citron Research, which is known as a short seller, affixed that label after human rights watchdog Amnesty International released a study earlier this week that declared the social media service “a toxic place for women.” In surveying the experiences of 800 journalists and politicians and analyzing 15 million tweets, Amnesty concluded that a women is abused every 30 seconds on Twitter, with 7% of tweets abusive or problematic. Women of color were 34% more likely than white women to be targeted, the study found.

“We have the data to back up what women have long been telling us–that Twitter is a place where racism, misogyny and homophobia are allowed to flourish basically unchecked,” Milena Marin, senior adviser for tactical research at Amnesty, said in a statement.

In lowering its price target to $20 a share, Citron declared the stock “uninvestable” and added that “advertisers will soon be forced to take a hard look at all sponsorships with Twitter.” The company’s stock closed at $29.20, with trading volume twice the average level.

Sheryl Sandberg, Facebook COO, center, and Jack Dorsey, Twitter CEO
Tom Williams/CQ Roll Call via AP Images

In a formal response to Amnesty International, Twitter’s policy lead, Vijaya Gadde, wrote that the company is committed to improving the civility of conversation on its service, and cracking down on abuse. The platform uses a combination of machine learning and human review to evaluate abuse reports to determine whether they violate Twitter’s rules. It provides follow-up notifications to the individual who reports it, makes available other sorts of tools to improve an individual’s experience, including the ability to block or mute another user.

“As numerous civil society groups have highlighted, it is important for companies to carefully define the scope of their policies for purposes of users being clear what content is and is not permitted,” Gadde wrote. “We would welcome further discussion about how you have defined “problematic” as part of this research in accordance with the need to protect free expression and ensure policies are clearly and narrowly drafted.”

The backlash follows a broader one against Facebook, which has made repeated mistakes that have allowed foreign entities to sway major elections and compromised the personal data of millions of users. The #DeleteFacebook movement has gradually picked up steam in recent months, especially after a damning New York Times account in November that showed the lengths the company was willing to go to in order to secure future growth.