Diamondback Capital Management, one of several hedge funds to be ensnared in the government’s insider trading investigations, will close down after investors asked to withdraw $520 million in capital, the firm wrote in a letter to investors on Thursday.

The money investors are seeking to pull out of the fund by year end amounts to about 26 percent of its assets, Diamondback wrote in the letter. It would leave the firm with $1.45 billion.