Affirm stock popped more than 15% Tuesday after the company announced it is expanding its partnership with Walmart to self-checkout kiosks in more than 4,500 of the retailer's U.S. stores.

Affirm shares have soared over 400% this year, one of the best performers across the U.S. stock market, after the company lost 90% of its value in 2022. With Tuesday's rally, the stock has surpassed its $49 IPO price from 2021 for the first time since early last year.

Walmart has an existing partnership with the buy-now-pay-later company that allows customers to purchase goods online and in-store from Walmart by pre-applying for credit and then showing a barcode to a checkout sales associate.

"Recent Affirm research revealed that more than half of Americans (54%) are looking for retailers to offer a buy now, pay later option at checkout," Affirm''s senior vice president of revenue Pat Suh said. "Moreover, we've found that 76% of consumers would either delay or not make a purchase without Affirm."

Affirm also has partnerships with Walmart competitors like Amazon and Shopify.