Here's the official statement from Games Workshop about the potential sale of Solaris:
GAMES WORKSHOP PUTS SOLARIS BOOKS IMPRINT UP FOR SALE
Games Workshop PLC today announced its intention to make its Solaris Books publishing imprint available for sale.
BL Publishing, the publishing division of Games Workshop, has two imprints, Black Library and Solaris. Its core business is the Black Library, an imprint which publishes fiction set in the dark fantasy worlds of Games Workshop’s Warhammer and Warhammer 40,000 settings. It has seen consistent double
digit like-for-like growth over the last 3 years.
Solaris is an original fiction imprint of BL Publishing and releases around 20 science fiction, fantasy and horror titles a year. Renowned for its back-to-basics approach and innovative marketing, this imprint was started in 2006 and has very quickly become established as a global brand in midlist, mass market fiction.
Both the Black Library and Solaris are distributed in the UK and US by Simon & Schuster.
Games Workshop’s Head of Publishing, George Mann, said in a statement: “In recent years our Black Library imprint has more than doubled in size and scope and we have decided that we should focus all our attention in growing this core part of our business. Whilst we see plenty of growth potential with
Solaris, we are looking for a buyer who is interested in developing this global brand.”
So you see, it's not - as some folk have suggested - a reaction to some sort of poor performance by Solaris. Instead, it's simply GW deciding that they're better off concentrating their efforts on the increasingly successful Black Library imprint, which is more relevant to their overall market.