Dive Brief:

• Amazon will reprise its "Digital Day" Dec. 28, with offers on digital content including movies, TV shows, mobile games, apps and e-books. Some deals will be available as early as Dec. 26, though the biggest savings will begin at midnight Pacific Standard Time the following Friday, according to a company press release.

• Deals include up to 75% off best-selling Kindle books, up to 80% off best-selling Marvel graphic novels, up to 60% off digital magazines and 25%-35% off digital games. The day also includes markdowns of devices that stream Amazon's content, like $50 off the Fire HD 10 tablet with a three-month free trial of its Audible audiobook service, the e-retailer said.

• In its third quarter, Amazon saw subscription services, which include annual and monthly fees associated with Amazon Prime membership, as well as audiobook, digital video, e-book, digital music and other non-AWS subscription service, grow 52% year over year to $3.7 billion, according to a press release.

Dive Insight:

Amazon has shifted to sell more through its third-party marketplace (more than half of what it sells is now through that), but its digital content is another area of growth.

The company's Amazon Music Unlimited and Kindle Unlimited subscriptions in particular have been "really popular" of late, Amazon CFO Brian Olsavsky told analysts in October, according to a conference call transcript from Seeking Alpha.

Like its Amazon Prime Video streaming service, which is free to the Prime members coughing up $119 each year for the program's many perks, devices in the Echo, Kindle and Fire lines help lock in customers to the Amazon ecosystem, and the company's Digital Day deals further that.

The e-commerce giant may need the boost. Amazon's U.S. Prime membership growth is showing signs of flattening, growing 8% in the past 12 months, the lowest annual rate since Consumer Intelligence Research Partners started tracking Prime in 2012. The investment research firm pegs U.S. Prime membership at 97 million, which is by far the bulk of what CEO Jeff Bezos last year revealed is 100 million members worldwide.

Digital Day is also a way for Amazon to combat the advantage of brick-and-mortar retailers. Starting on Wednesday, customers can visit amazon.com/digitalday and sign up to be notified when the deals begin, and they can shop the sale from their desktop or mobile device or from an Amazon Fire tablet, Fire TV or Kindle devices, the company said.