What happened

Shares of StoneCo (STNE 0.26%), gained ground on Tuesday morning, jumping as much as 7.2%. As of 3:47 p.m. ET, the stock was still up 6.8%.

The catalyst that sent the Brazilian fintech higher was positive commentary from a Wall Street analyst.

So what

Susquehanna analyst James Friedman dug deeper into StoneCo's recent earnings report and came away with a positive outlook. He was particularly impressed by the result of the company's robust total payment volume (TPV), which was much better than expectations. 

In conjunction with its second-quarter financial report, which was released on Aug. 18, StoneCo reported revenue of 2.3 billion Brazilian reals (roughly $451 million), an increase of 83% year over year, fueled by the company's financial services businesses, which grew 102%.

The biggest contributor to this performance was its record-setting TPV of 90.7 billion reals (roughly $17.8 billion), driven by strong gains in its micro-, small- and medium-sized businesses segment. The company also swung to a profit from a loss in the year-ago quarter.

Friedman maintained both his positive (buy) rating and $20 price target on the stock, while boosting his TPV growth estimate from 16% to 24%.

Now what

Warren Buffett's Berkshire Hathaway (BRK.A 1.18%) (BRK.B 1.30%) was an early investor in StoneCo, laying out $340 million to get in on its 2018 initial public offering (IPO). It's important to note that reports later confirmed that it wasn't Buffett himself but portfolio manager Todd Combs who actually completed the transaction. 

The company has had a rough go of it thus far, with its shares down roughly 70% since its debut. Berkshire hasn't given up on the little fintech that could, however. According to its most recent regulatory filings, the company still holds roughly 10.7 million shares of StoneCo stock, valued at about $98.7 million at current prices. 

That's a pretty strong vote of confidence in the beleaguered fintech company. StoneCo is incredibly cheap right now, selling at less than 2 times forward sales. Given the company's robust growth and its large and growing opportunity in Latin America, it's no wonder Buffett continues to hold on tight. StoneCo stock looks like a buy.