DoubleLine Capital, which oversees some $90 billion in assets, is shutting down its three-year old DoubleLine Equities Growth Fund, a spokesman said on Wednesday.

The $5.9 million DoubleLine Equities Growth Fund will stop operating after failing to gain much traction with investors and posting poor returns.

The fund has lost 12.27 percent since January, public data show, leaving it to lag 94 percent of its peers in the large-cap growth space, research firm Morningstar said.

A DoubleLine spokesman said the company decided to shut the fund down at a time investors are more interested in index funds rather than actively managed funds.

"DoubleLine and the DoubleLine Funds Board of Directors decided to liquidate the fund and return the proceeds to investors," spokesman Loren Fleckenstein said in an email. "DoubleLine will focus its equities investment programs on rules-based approaches such as Enhanced CAPE, which to date has gathered nearly $1 billion in assets in less than three years," he added.

Performance at the fund was equally poor in 2015, when the fund also trailed 94 percent of its peers and ended the year with a 3.72 percent loss, according to Morningstar.

"The fund does not seem to be gaining ground on its competitors and investors have largely ignored it from the beginning," said Jeff Tjornehoj, head of Americas research for Lipper, a Thomson Reuters company.

Some of the decline may have been fueled by the fund's concentrated holdings, including bets on e-commerce company Amazon, holding company Leucadia National Corp. and electronic instrument maker Ametek Universal Corp., which have all posted double digit losses this year.

DoubleLine launched the fund three years ago with a goal to deliver "long-term capital appreciation," but raising assets was difficult and the fund had only $8.3 million at its peak in the middle of 2015.

Brendt Stallings has run the fund since its launch in April 2013.

DoubleLine founder Jeffrey Gundlach said recently that the firm purchased stocks last month after the market tumbled early in the year.