Snap's list of worries is growing longer: It's strapped for cash and will likely be forced to raise capital as early as mid-2019, according to one Wall Street research firm.

"While it is obvious that Snap wasn't prepared for life as a public company, it now has a more pressing problem. It is quickly running out of money," analyst Michael Nathanson of MoffettNathanson wrote Tuesday.

Nathanson cut his 2019 revenue estimates by 7 percent and his 2020 estimates by 15 percent, forecasting both slower user growth as well as slower revenue per user growth.

Snap did not respond to CNBC's request for comment.