According to a European Commission press release, Apple and Amazon agreed to end the exclusivity deal on January 5th. The pact was actually signed before Amazon acquired Audible (back in 2008), but the German Publishers and Booksellers Association believed Amazon's actions were damaging publishers' ability to sell their work via "alternative channels."
At the time, around 90 percent of all audiobook downloads in Germany were made via Audible or Amazon websites, or via the iTunes Store, indicating why publishers and booksellers had decided to complain.
Commenting on the settlement, the European Commission said it "welcomes an agreement to end all exclusivity obligations concerning audiobook supply and distribution between Amazon's subsidiary Audible and Apple." The competition regulator believes it will also "improve competition in downloadable audiobook distribution in Europe" as Apple can source audiobooks from different suppliers, while publishers can directly secure their own distribution agreements with Apple.
It's not the first time that Apple and Amazon have been embroiled in an antitrust investigation. In 2012, the US Justice Department sued Apple, Hachette, HarperCollins, Macmillan, Penguin and Simon & Schuster over alleged e-book price-rigging.
The agreement was designed to stop booksellers like Amazon and Barnes & Noble from selling bestsellers at a loss. Apple and its co-conspirators were forced to settle out of court. However, it took until mid-2016 for iBooks price fixing credit to make its way to those who opted in to a class action lawsuit against the Cupertino company.