Publishers Lunch is reporting that Hachette Book Group has acquired the publishing and distribution company Perseus Books Group in “an unusual three-way transaction,” with a formal announcement expected from Hachette later today.

According to Publishers Lunch:

Hachette Book Group is purchasing PBG, and then in turn will sell to Ingram Content Group Perseus’s extensive distribution companies – including Perseus Distribution, PGW, the recently formed Legato, and Consortium, plus the Constellation digital distribution platform and their share in the U.K. joint-venture Faber Factory Powered by Constellation. What HBG retains is Perseus’s own, almost entirely nonfiction publishing imprints, comprising Basic, Public Affairs, Running Press, Avalon Travel, Seal Press, academic textbook publisher Westview Press, the Weinstein Books joint-venture and a partnership with Nation Books – and our understanding is that Hachette intends to take on all of those publishing divisions intact, as well as all of the publishing locations from which those units operate.

Hachette currently stands as the fourth-largest publisher in the U.S., with PBG following in sixth place. However, the merger “would result in a smaller company than Penguin Random House,” according to The New York Times.

The deal is expected to close by July 31 and will be subject to government review.