New York (CNN Business) Shares of Affirm Holdings, the recently public fintech firm, soared more than 40% Monday morning following news that it is partnering with Amazon (AMZN) to roll out its buy-now-pay-later function for some purchases over $50.

"By partnering with Amazon we're bringing the transparency, predictability and affordability that Affirm provides today to the millions of people who shop on Amazon.com in the U.S.," Eric Morse, senior vice president of sales at Affirm, said in a press release.

"Offering Affirm's alternative to credit cards also delivers more of the payment choice and flexibility consumers on Amazon want," Morse added.

The companies also said in a press release that they are rolling out the program to some Amazon shoppers now, but that over the next few months "Amazon plans to make Affirm more broadly available to its customers."

PayPal PYPL Affirm, which went public in January , is led by CEO and founder Max Levchin, who is also a co-founder of