Groupon Inc.’s take rate, which is the commission it takes from the sale of vouchers and other products, is on the rise, which explains why the daily deal operator was able to post its first-ever operating profit in the first quarter, according to data compiled by daily-deal aggregator Yipit.

The daily deal operator’s take rate was 41% in the first quarter, up from 40% in the fourth quarter and 37% in the third quarter of last year.

That’s despite Groupon’s online marketplace Groupon Goods accounting for a increasing portion of the daily deal operator’s North American business. Groupon Goods, which launched at the tail end of September, is widely believed to have lower margins than Groupon vouchers that can have a take rate as high as 50%.

Groupon Goods represented 10% of the company’s North American gross billings in the first quarter, up from 6% in 2011’s fourth quarter and 1% in the third quarter.

Groupon’s increasing take rate suggests Groupon Goods might be more profitable than many experts had thought, writes Sean Spielberg, a Yipit data analyst, in a blog post. “Groupon’s massive distribution and ability to instantly monetize large quantities of unused inventory may have given Groupon more negotiating leverage,” he writes.