NEW YORK (CNN/Money) - Amazon.com said Friday it finished the best holiday season in its history, capped by a single-day record in terms of units sold.

Amazon.com (AMZN: Research, Estimates) ended with small gains after rising as much as 3 percent earlier in the session.

The nation's largest online retailer said it set a single-day record with more than 2.1 million units ordered worldwide -- or 24 items per second -- although Amazon spokesman refused to specify which day set the sales record.

Amazon also said it sold 70,000 gift certificates on Dec. 24, and shipped more than 1 million packages on the peak day this season.

YOUR E-MAIL ALERTS Amazon.com Retail Electronic Commerce or Create your own Manage alerts | What is this?

"Offering more selection than ever and low prices helped our customers find exactly what they were looking for this holiday season," Senior Vice President Jeff Wilke said in a statement.

Amazon said its best sellers this year included digital cameras, CDs, DVDs and sporting goods. Electronic shavers and books also were some of the popular items.

Shares of Amazon.com have nearly tripled this year. The stock started 2003 at around $19 a share.