Despite its exuberant initial public offering in March, Snapchat parent company Snap has since had a bumpy ride. C.E.O. and co-founder Evan Spiegel saw his fortune spike to $6 billion on the fourth day of Snap’s existence as a public entity, but the company shared a bleak earnings report last month. Now, Snapchat, which is currently valued at about $22 billion, has the highest short interest of the 14 U.S. tech and communications companies to go public this year, Bloomberg reports. Short interest—the amount of money investors bet against a company—in Snap has risen to about 28 percent of the shares available to the public, or more than $1 billion.

Much of the bearishness on Wall Street is likely tied to the fact that Snap’s first stock lockup expires on July 30, the date when some stakeholders and executives can finally sell their shares. “It looks like short-sellers are positioning themselves for a dramatic selloff in Snap’s stock price after the lockups expire,” Nomura Instinet’s Anthony DiClemente said in a note to his firm’s clients on Wednesday. Still, there are plenty of other reasons traders may be looking for Snap to drop. New app download data suggest a slowdown in Snapchat’s daily active user growth, which is a key metric for social-media companies (at this point after its I.P.O., Facebook had half as much short interest as Snap now does, Bloomberg notes). DiClemente said that downloads of Snapchat dropped 22 percent in April and May, according to statistics from mobile-app analytics firm SensorTower. Downloads on iPhones have dropped by more than 40 percent in the same two-month span. By comparison, in the first three months of 2017, Snapchat downloads actually rose 6 percent. (Snapchat did not immediately respond to a request for comment.)

Snapchat, of course, also has a formidable opponent in Instagram, which Facebook has been using to effectively clone successful elements of Snapchat and deploy them to Instagram’s 700 million monthly active users. The strategy, which may have frightened some investors, seems to be working: in April, Facebook announced that Instagram Stories now has 200 million daily active users. That’s a 33 percent jump since January, when Instagram hit 150 million daily users, showing just how quickly Facebook can increase engagement by leveraging its massive user base against competitors. In total, Snapchat has 166 million daily active users. “By comparison, Instagram downloads have demonstrated YoY growth, suggesting that competitive pressures may be intensifying for Snap, challenging the platform‘s ability to attract and retain new users,” DiClemente said in his note.