Greenlight Capital Inc., a hedge fund run by David Einhorn, was forced to pay back more than $400 million in clients withdrawals at midyear, the Wall Street Journal reported on Thursday, citing sources.

More than 15 percent of eligible investors chose to redeem their money, people close to the hedge fund told the newspaper.

Greenlight, a U.S.-stock specialist, was down 2 percent in the first half of the year, while the S&P 500 gained 9 percent, including dividends, according to the paper.

The fund has been closed to new investment since late 2014, people familiar with the matter told WSJ. (http://on.wsj.com/2tLQW7Y)

Greenlight representatives did not immediately respond to a request for comment. (Reporting by Sruthi Shankar in Bengaluru; Editing by Sriraj Kalluvila)