US authorities have reached a settlement with Macmillan, the last of five publishers accused of colluding with Apple in an e-book price-fixing conspiracy.
The US Justice Department said in a statement that with the five publishers having settled, the case will proceed against Apple, and that a trial had been set to begin in June.
Macmillan joined Penguin Group, Hachette Book Group, HarperCollins and Simon & Schuster in settling the charges of an illegal conspiracy to raise e-book prices.
Macmillan agreed to immediately lift restrictions it has imposed on discounting and other promotions by e-book retailers, and its practices will be monitored under the settlement.
US officials allege the price-fixing scheme was aimed at ending a discounting effort by Amazon, which sold most e-books at $US9.99 until Apple's new pricing plan was forced on the retail giant.
The move almost instantly raised the prices consumers paid for e-books to $US12.99, $US14.99 or higher, according to the US complaint.
"As a result of today's settlement, Macmillan has agreed to immediately allow retailers to lower the prices consumers pay for Macmillan's e-books," said Jamillia Ferris of the Antitrust Division at Justice.
"Just as consumers are already paying lower prices for the e-book versions of many of Hachette's, HarperCollins' and Simon & Schuster's new releases and best sellers, we expect the prices of many of Macmillan's e-books will also decline."
According to the lawsuit filed last April, the five publishers and Apple were unhappy that Amazon's efforts had reduced e-book prices and the retail profit margins of the book sellers to levels they thought were too low.
The suit filed in US District Court in New York said a conspiracy dating back to 2009 involved "schemes to limit Amazon's ability to discount e-books", hurting consumers by pushing up prices.
Macmillan's parent firm Holtzbrinck Publishers LLC is owned by German-based Verlagsgruppe Georg von Holtzbrinck GmbH.
