Famed producer Bob Rock has sold his rights to Metallica’s 1991 chart-topping "Black Album" to the Hipgnosis Songs Fund. Louder.com reported that Rock also sold the rights for the songs he produced for singer Michael Bublé to the firm owned by Merck Mercuriadis. The "Black Album" has sold over 31 million units globally — with Rock earning a royalty on ever copy sold.

Rock, a Canadian, is also best known for his work with such A-listers as Mötley Crüe, Bon Jovi, Aerosmith, the Cult, Bryan Adams, the Offspring, David Lee Roth, and Ron Sexsmith, among many others. He was also featured prominently in Metallica's 2004 documentary, Some Kind Of Monster.

Bob Rock said in a statement announcing the deal: "I put my heart and soul into these recordings. I know how much Merck loves music, so it was an easy deal to put together."

Merck Mercuriadis added "The breadth of Bob Rock’s enormous successes are almost impossible to match by any creator in the history of music. From Metallica’s most famous 'Black Album' to Michael Bublé’s Christmas, he has produced some of the biggest albums of all time that continue to be evergreen, year in and year out."

The "Black Album" was Metallica's biggest commercial breakthrough, producing five singles and making them one of the most popular rock bands in the world. Former bassist Jason Newsted told us that at the time, Metallica was eager to make a big leap forward: ["Everybody was ready. We pulled in somebody that could control us for a second and harness us for a second. That transpired. Everybody put their nose to the stone and worked hard, like Metallica always did, and then we got the fruits from it. Years later, it's still, well, maybe is the biggest selling album in America for, I don't know, for a long time."] SOUNDCUE (:16 OC: . . . a long time)

Jason Newsted Recalls Making Metallica’s ‘Black Album’ :