Snap Inc. (SNAP.N) shares jumped to their highest level since early September after finally winning over BTIG, which set a Street-high price target of US$15.

"Virtually everything that could go wrong for Snapchat over the past couple years since going public has gone wrong," wrote analyst Rich Greenfield, who upgraded the stock to buy.

Greenfield noted a surge in North America spending from advertisers based in the rest of the world, likely mostly Asia, during the second half of 2018 and should benefit revenue growth this year. He’s increasingly confident that overseas direct response/performance advertisers are taking advantage of low relative bid prices on ad inventory in the U.S.

Greenfield in September downgraded the stock to sell before growing more positive about three months later, raising the rating to neutral. In a note, Greenfield spelled out several other reasons for his now-bullish view, ranging from a "less seedy" Discover section and improving morale.

He expects that Snapchat will further separate its professional and user-generated content within the Discover section. This will lead to a better user experience and increase the attractiveness of to advertisers. "We have repeatedly highlighted the low-quality, clickbait feel of Snapchat’s Discover section," Greenfield wrote.

BTIG also noted that the newly rebuilt Android app has been performing notably better, especially within the Discover section. Users are coming onto the platform for the first time, he said.

These improvements, along with some executive hiring and a clear strategic roadmap, has led to a more upbeat mood within the company, Greenfield said. "2018 was an awful year for Snapchat with morale at all-time lows," he wrote. "We can feel the improved morale and momentum internally."

--With assistance from Kamaron Leach