They packaged the royalty stream from his music creations and issued what became known as "Bowie bonds." A kind of intellectual property backed security. This occurred long before subprime mortgage securities came on the scene.
The BBC reports (my emphasis):
David Bowie was a pop music icon to many, but how many people know he was also involved in innovation in the world of finance?
In the mid-1990s, David Bowie, his financial manager Bill Zysblat, and banker David Pullman came up with a new scheme to generate cash from Bowie's extensive back catalogue.
In 1997 Bowie sold asset-backed securities, dubbed "Bowie bonds", which awarded investors a share in his future royalties for 10 years.
The securities, which were bought by US insurance giant Prudential Financial for $55m (£38m), committed Mr Bowie to repay his new creditors out of future income, and gave a fixed annual return of 7.9%...
Bowie used part of the $55m to buy out his former manager Tony DeFries, with whom he had split with in 1975, says music writer Paul Trynka.
Mr Bowie's realisation in the 1970s that he didn't own all the rights to his catalogue - Mr DeFries reportedly owned up to 50%, on a sliding scale, in perpetuity, for music created up to a certain point - had caused Bowie to have a mental breakdown of sorts, Mr Trynka says.
"He had this psychological nose-dive - all this music he had suffered to create didn't [entirely] belong to him."
An example of great financial creativity and also a blow to those who think simply because the creator of songs still "has them in his head," that he may not want more control over his creations then just "in his head.".