Even after payments company Square's stock price quadrupled in a year, one analyst is betting that the shares are still cheap.

Guggenheim raised its price target to $100 from $75 Wednesday and named Square its "new best idea" and "highest conviction name" in fintech.

The new target is about 24 percent higher than Tuesday's closing price. Shares closed 6 percent higher following Guggenheim's call, and have seen a 227 percent increase year over year. This year alone, Square is up more than 136 percent.

Guggenheim analyst Jeff Cantwell said in a note to clients Wednesday that he sees revenue coming in significantly higher than the Street's current consensus. "We expect a strong rate of revenue growth for SQ which should drive further share price appreciation."

The firm also named Square its "best idea" two years ago because of what it considered low fourth-quarter 2016 revenue forecasts.

Since then, Square has shifted from its "micromerchant" roots to a focus on selling value-added services, Guggenheim said. The firm predicts Square will generate "substantially higher" subscription and services-based revenue than analysts are expecting for the end of 2019 and beyond.

Guggenheim's revenue estimate is 10 percent above the consensus forecast for adjusted revenue in 2019, according to Cantwell.

In its most recent quarterly report, Square beat Wall Street estimates thanks in part to higher transaction volumes, but the company came up slightly short on adjusted EPS guidance for the third quarter.