• by Gavin O'Malley  @mp_gavin, January 31, 2020

Thanks, in part, to its sturdy ad business, Amazon posted better-than-expected fourth-quarter earnings this week.

What the tech titan calls “other revenue” -- mostly made of ad dollars -- approached $4.8 billion during the period, which was up 41%, year-over-year.

That figure was in line with estimates from around the industry and generally left analysts impressed. “Very strong advertising revenue growth,” RBC Capital’s Mark Mahaney remarked in a note to clients.

The growth also shows Amazon’s ad business is maintaining its momentum from quarter to quarter, according to David Fildes, director of investor relations at the company.

“Our advertising revenue is … growing at about the same rate year-over-year in the fourth quarter as … it did in the third quarter,” Fildes said on Amazon’s earnings call this week.

Regarding Amazon’s ad strategy, Fildes said the company remains focused on deepening brand engagement and customer loyalty.

Advertising only constitutes a small share of Amazon’s overall revenue, which totaled nearly $87.5 billion in the fourth quarter. It was up by 21%, year-over-year.

For his part, Amazon founder-CEO Jeff Bezos seemed most excited about the company’s Prime membership numbers.

“More people joined Prime this quarter than ever before, and we now have over 150 million paid Prime members around the world,” Bezos said in an earnings statement.

During the period, the continued success of Prime was largely during to the success of its one-day and same-day delivery services, according to Bezos.

Stateside, free one-day and same-day deliveries more than quadrupled from the fourth quarter of 2018 to the fourth quarter of 2019. Prime subscribers watched double the hours of original movies and TV shows on Prime Video this quarter, compared to last year, while Amazon Originals received a record 88 nominations and 26 wins at major awards shows.