Revenue at Penguin Random House fell 3.3% in the first half of 2018 compared to the same period a year ago, dropping to €1.48 billion from €1.53 billion a year ago, parent company Bertelsmann reported. Earnings fell 17.0%, from the first six months of 2017, with EBITDA (earnings before interest, taxes, depreciation, and amortization) declining to €171 million.

Both Bertelsmann and PRH chairman Markus Dohle attributed the decline in results, in large part, to the negative impact of exchange rates. In his letter to employees, Dohle explained that while “headline” figures were down, excluding the impact of exchange rates “underlying operating revenue and profit numbers for Penguin Random House in U.S. dollars have been stable year over year. This means that the quality of our business and our earnings have been on the same—high—level as in the prior year. Our core business remains very strong globally.”

Double-digit gains in audiobook sales were a highlight of the first half, and PRH continued to publish numerous bestsellers, placing 178 titles on the New York Times bestseller list in the first half of 2018. Among the books that sold the best in the period, Bertelsmann said, were The President Is Missing and 12 Rules for Life, as well as Ernest Cline’s novel Ready Player One, which served as the basis for the eponymous Steven Spielberg movie and was also successful as an audiobook.

First half results also include the purchase of Rodale’s book group in the U.S. and of Hind Pocket Books in India. In his letter, Dohle also pointed to the creation of “multiple new and innovative imprints, among them Kokila at Penguin Young Readers and Random House Graphic at Random House Children’s Books in the U.S.”

The first six months of 2018 also saw PRH make more investments in its supply chain, Dohle wrote, including the opening of a new building in the U.S. to expand the capacity of PRH’s Maryland facility. “These large investments continue to help us enhance the efficiency and profitability of our booksellers—and of our own company,” Dohle wrote. “Millions of readers are newly enjoying direct relationships with us, thanks to the data-driven consumer insights and relationships we are developing to market our books directly and at scale.”

Looking at the remainder of the year, in addition to numerous likely bestsellers, PRH will publish Michelle Obama’s Becoming on November 13, in 24 languages.

Coming off of a flat first half of 2018, Dohle closed his letter by noting: “We are clear-eyed about our current and future challenges, and we have a clearly-shaped strategy to meet those challenges. That’s why I remain optimistic about the immediate and long-term future of book publishing and the position we have created together in our core businesses around the world.”