One gamble that paid off for Howard Marks, co-founder of Los Angeles distressed-debt manager Oaktree Capital Group, was his $20 million investment in 2009 for a one-fifth stake in DoubleLine Capital, founded by Jeffrey Gundlach.

Gundlach had paid out $158 million in income to Oaktree over the last five years, repaying the original investment almost eightfold, Bloomberg reported on Thursday. That stake may now be worth as much as $900 million, according to estimates by analysts who follow Oaktree.

Gundlach’s success has translated into a growing stream of cash for Oaktree, and its single biggest source of investment income last year.