(Reuters) - Affirm shares jumped 16% in premarket trading on Friday, after the buy now, pay later lender posted a surprise quarterly profit on the back of a strong holiday shopping season and forecast an upbeat annual revenue.

Retailers offered discounts on everything from apparel to electronics to lure budget-conscious shoppers, while online sales remained strong.

Gross merchandise volume (GMV) - the total dollar amount of all transactions on the Affirm platform - jumped 35% to $10.1 billion in the second quarter ended December 31, exceeding analysts' estimates of $9.57 billion, according to LSEG.

Affirm was on track to add roughly $3 billion to its market capitalization if the gains hold.

In a letter to shareholders late on Thursday, Affirm said the merchandise and consumer electronics categories contributed significantly to growth.

GMV growth from Affirm's top five merchants and platform partners collectively jumped 40%, partly due to increasing demand from consumers for zero-percent financing.

The San Francisco, California-based company's total revenue soared 47% to $866 million, beating estimates of $807.2 million.

"Affirm is on our short list of transformative fintechs that can become big companies over time," William Blair analyst Andrew Jeffrey said.

Affirm reported net income of $80.4 million, or 23 cents per share, in the October-to-December period, compared with a loss of $166.9 million, or 54 cents per share, a year earlier.

Analysts had expected the company to report a loss of 15 cents per share.

"So far other fintech results have been lackluster this quarter, with some posting significant growth guidance but weak profitability. In contrast, Affirm demonstrated that a fintech can have both strong volume growth and excellent profitability margin," BTIG analysts said.

Affirm also forecast fiscal 2025 revenue between $3.13 billion and $3.19 billion, largely above Street expectations of $3.09 billion.