By KEN BELSON

Linsanity may have cooled a bit after the Knicks lost two games in recent days. But by one measure, the fervor for Jeremy Lin, the sensation also known as the Knicks’ point guard, is as heated as ever: A mint condition rookie trading card of Lin sold for $21,580 on Thursday afternoon.

That proved to be quite a payday for Yair Rozmaryn, a card collector in Manhattan who bought the card for $1,000 two weeks ago. At the time, Lin had starred in only two games. Rozmaryn had the card appraised and then auctioned it on eBay over the past week.

The card is 17th in a series of 25 cards issued and was therefore more valuable, Rozmaryn said, because 17 is Lin’s number.

After news of the auction was reported in The New York Times and elsewhere, Lin sent an e-mail to Rozmaryn. It was unclear what Lin hoped to do because he and his agent, Roger Montgomery, did not respond to e-mails asking whether Lin wanted to buy the card himself or help promote the sale of the card for charity or some other cause.