Amazon.com Inc. (AMZN) appears to have had a great Christmas.

The online retailer announced that it enjoyed a "record-breaking" holiday season, in a press release published on Wednesday, adding that customers around the world ordered more items from its website during the Christmas shopping season than ever before.

The Seattle, Washington-based company’s signature membership program was also in hot demand as customers sought to take advantage of its quick delivery service to ensure that gifts arrived in time for Christmas. Amazon said “tens of millions” of people signed up for Prime memberships during the period and that more than 1 billion items were delivered through the $119-a-year subscription service in the U.S. alone.

And Amazon wasn't coy about it; the word "Prime" appears a total of 32 times in the release.

"This season was our best yet, and we look forward to continuing to bring our customers what they want, in ways most convenient for them in 2019," Jeff Wilke, CEO of Amazon's worldwide consumer business, said in the press release.

Ticking the Right Boxes

News that Amazon attracted millions of new Prime members was arguably a key catalyst for the share price rising 9.45% on Wednesday. The Nasdaq Composite index was up 5.84% on the day. The subscription service offers investors an important glimpse at how many loyal customers the company has and is widely considered to be a key growth driver for Amazon.

Prime members spend on average $1,300 per year on Amazon, according to data from Consumer Intelligence Research Partners, $300 more than non-Prime members. Importantly, data also shows that once the company wins new subscribers, it seldom loses them — renewal rates top 90%, according to the data.

Investors know that Prime numbers are good for Amazon, although there is still no way to establish just how much they impact quarterly financial figures. The Securities and Exchange Commission is pressing Amazon to be more transparent by disclosing how much revenue it generates from Prime, according to Quartz. However, Amazon continues to maintain that providing this information is not “meaningful or useful.”

Other than Prime, Amazon has also made a habit of bragging about how many of its own devices it sells. The company said it sold "millions more" Amazon Devices this year, listing its entry-level Alexa speaker, the Echo Dot, at the top of its list of best-selling products.

Leading the bestsellers across other categories were L.O.L. Surprise! Glam Glitter Series Dolls, Carhartt attire and Bose QuietComfort headphones.