TORONTO -- Canadian record producer Bob Rock is joining a chorus of musicians selling off rights to their past work, reaching a deal with a U.K. investment firm for more than 40 songs from Michael Buble and Metallica.

The agreement between Rock and Hipgnosis Songs Fund, announced Thursday, will give the London-based operation Rock's full producer rights to a raft of prominent tracks.

Among them is Rock's stake in Metallica's self-titled 1991 album, often called "The Black Album," which includes the metal band's hits "Enter Sandman," "The Unforgiven" and "Nothing Else Matters."

He's also sold his rights to Buble's album "To Be Loved" in its entirety and his work on "Call Me Irresponsible," "Crazy Love" and "Christmas."

Rock, who was born in Winnipeg, is one of Canada's most prolific rock music producers, having worked with the Tragically Hip, Aerosmith, Bryan Adams and Bon Jovi.

The Hipgnosis deal, which encompasses 43 songs, comes as the fund moves quickly to build its library of rights holdings.

Last week, Hipgnosis picked up the publisher and songwriter rights to Shakira's entire catalogue of 145 songs, and earlier this month acquired a 50 per cent stake in Neil Young's catalogue of 1,180 songs.

Rights deals have become a hot commodity in the pandemic as artists look to monetize their assets while the touring industry remains at a standstill and listening moves increasingly to streaming platforms over record sales.

Each transaction can be slightly different than the next, depending on what rights the creator is selling.

For instance, sound recording copyrights cover the song that's committed to tape in the studio and can include revenues spanning from album sales and streaming to licensing for commercials and TV shows.

Publishing rights cover the rights for the musical work that's committed to paper. Typically that means a slice of revenues from live performances as well as licensing fees from covers recorded by other artists.

Bob Dylan recently sold publishing rights to more than 600 songs to the Universal Music Publishing Group for estimates that were priced between $300 million and half a billion dollars. Stevie Nicks sold an 80 per cent stake in her music to Primary Wave for a reported $100 million.

This report by The Canadian Press was first published Jan. 21, 2020.