Snap could go private if it can't get people to stay on its Snapchat app for longer and improve its monetization, according to a Wall Street research firm.

Snap, parent company of Snapchat, started publicly trading in March 2017 but has shed $20 billion in market capitalization since then and has struggled to attract new users.

"The data we look at is showing a widening user base, although one which is collectively reducing its time on the platform," said Brian Wieser, a senior research analyst at Pivotal Research Group, in an email to CNBC.

"Our take is that it is not too late for management to find ways to reverse recent usage trends and generally improve monetization regardless of those usage trends. With ongoing experimentation, we have some faith that they should be able to do both."

"At the same time, if they are unable to do so in the near term, the company could become an attractive candidate to go private with the stock's price at current levels," Wieser added. However, he remained positive overall about the stock and upgraded it from a "hold" to a "buy" in a recent research note.