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 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.”

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

The stock nearly doubled from its offering price of $49 on its first day of trading and hit a peak of about $146 in February before tumbling back to Earth. Shares now trade around $96 following Monday’s pop.

Affirm is a leader in the buy-now-pay-later area of e-commerce. But there is a lot of competition. Levchin’s old firm PayPal is dipping its toe in the sector. PayPal rival Square (SQ) recently announced a $29 billion acquisition of Australian firm Afterpay for $29 billion.

There’s also Klarna, a Swedish startup currently valued at nearly $46 billion. That makes it the world’s fourth most valuable privately-owned unicorn, according to CB Insights. Klarna trails only Chinese TikTok owner Bytedance, payment processing firm Stripe and Elon Musk’s SpaceX.

Affirm is now worth about $25 billion.