Write a question about the following article: Penguin Books Ltd.  of the United Kingdom was bought over by Pearson Longman in 1970. Penguin Group  Inc. was formed in 1996 as a result of the merger between Penguin Books USA and the Putnam Berkley Group. The newly formed company was originally called Penguin Putnam Inc., but, in 2003, it changed its name to Penguin Group  Inc. to reflect the parent Pearson PLC's grouping of all the Penguin companies worldwide under the supervisory umbrella of Pearson's own Penguin Group division. The different Penguin companies use many imprints, many of which used to be independent publishers. Penguin Group  Inc. also operates its own speaker's bureau that books speaking engagements for many of the publisher's authors. In 2011, the online writing and publishing community Book Country was launched as a subsidiary of Penguin Group USA. In April 2012, the United States Department of Justice filed United States v. Apple Inc., naming Apple, Penguin, and four other major publishers as defendants.  The suit alleged that they conspired to fix prices for e-books and weaken Amazon.com's position in the market in violation of antitrust law. In December 2013, a federal judge approved a settlement of the antitrust claims, in which Penguin and the other publishers paid into a fund that provided credits to customers who had overpaid for books due to the price-fixing. In October 2012, Pearson entered into talks with rival conglomerate Bertelsmann, over the possibility of combining their respective publishing companies, Penguin Group and Random House. The houses were considered two of the Big-Six publishing companies, prior to the merger, which became the Big-Five publishing houses upon completion of the combination. The European Union approved of the Penguin Random House merger on 5 April 2013; Pearson controls 47% of the publisher.

Question about the article:
Which event happened first, Penguin Group Inc. forming, or US Department of Justice filing United States v Apple.