Billionaire investor Julian Robertson is closing Tiger Management Advisors LLC's Tiger Accelerator Fund and has pulled out of Ratan Capital Management LP as hedge funds fight against investor exits amid high fees and weak returns, Reuters reported, citing regulatory filings.

The Tiger Accelerator Fund, a group of six individual funds that allows investors to bet with Robertson, suffered a steep decline in outside capital to $28.5 million as of Dec. 31, 2016, from $450 million at its launch in 2011, according to the report.

Teewinot Capital Advisors LLC stopped handling the Tiger Accelerator portfolio's money in the third quarter of 2016, the news outlet reported, citing "a source familiar with the matter."

Robertson has also completely exited Ratan Capital Management, which used to manage more than $1 billion, but only had $375 million as of Dec. 31, 2016.