What happened

Shares of Affirm Holdings (AFRM -0.74%) rocketed 34.4% on Friday after the payment network's fiscal 2021 fourth-quarter growth metrics dazzled investors. 

So what

Affirm's revenue surged 71% year over year to $261.8 million. The gains were fueled by a 106% rise in gross merchandise volume (GMV) -- the total dollar amount of all transactions conducted on Affirm's platform, net of refunds -- to $2.5 billion.

A finger is pressing a keyboard button labeled buy now.

Affirm's flexible payment options are proving popular with shoppers. Image source: Getty Images.

Both businesses and consumers are flocking to Affirm's network. Active merchants soared 412% to nearly 29,000, driven in part by Affirm's partnership with e-commerce leader Shopify.

Meanwhile, active consumers jumped 97% to 7.1 million. People are also using Affirm's services more often, with transactions per active consumer rising 8%, to roughly 2.3.

Now what

Investors were no doubt pleased by Affirm's upbeat forecast for the year ahead. Management expects Affirm's revenue to grow by roughly 35% to $1.2 billion in fiscal 2022, driven by a 52% increase in GMV, to $12.6 billion.

Better still, these figures are likely to prove conservative, as they don't include any benefit from Affirm's partnership with online retail-titan Amazon.com. The two companies plan to bring Affirm's "buy now, pay later" services to Amazon's customers in the coming months.