After a large selloff in Snap shares since its IPO, a big Wall Street backer is jumping off the bandwagon less than three months after telling clients to buy, citing concerns the Snapchat parent will lose more money for longer than expected.

Citi Research lowered its rating on the social-media firm to neutral from buy Thursday.

Snap’s “pace of growth in monetization (including the contribution from new channels such as self-serve) may not be as fast as we had originally modeled in 2H17 due, in part, to a slower than expected roll-out of these new channels/platforms,” analyst Mark May wrote in a note to clients.

May lowered his price target for Snap to $20 from $24, representing 6 percent upside from Thursday’s close.

“Given continued Android issues, summer seasonality, heightened competition and the nature of Snap’s social network, we expect user growth will remain modest near term,” he wrote.

As a result, the analyst reduced his Snap second-quarter daily active users net adds estimate to 9 million from 12 million. In addition, he lowered his 2018 earnings per share estimate for the company to a loss of 46 cents from a loss of 42 cents.

Snap disappointed investors when it posted first-quarter results in May, which missed analysts’ sales and user growth estimates.

Nearly 70 percent of Wall Street does not have buy ratings on Snap shares, according to FactSet. Such a mixed view so soon after a large technology IPO is a rarity.

Snap stock chart since IPO

Source: FactSet

Snap shares are down 36 percent from its high, reached days after the company went public on Mar. 2. It is now only 11 percent above the $17 IPO price. Citi initiated with a buy rating on March 27th.

The analyst also cited Snap’s large share lockup expiration in the coming months as a reason for his downgrade.

“The expiration of the IPO lock-up in August will increase the stock available for sale (float) by >500% or 949mn shares, which could pressure shares (especially during this period in the company’s cycle),” he wrote.

Many insiders are restricted from selling stock for an agreed upon lockup period after the initial public offering, but that changes this summer when more shares will likely come onto the market.

Snap did not immediately respond to a request for comment for this story.

Disclosure: CNBC parent NBCUniversal is an investor in Snap.

— CNBC’s Michael Bloom contributed to this story.