By Svea Herbst-Bayliss

BOSTON (Reuters) - Hedge fund firm AQR Capital Management suffered more losses recently, prompting some investors to consider leaving one of the world's biggest quantitative funds.

The secretive $38 billion hedge fund, which like other "quants" relies on computer models to make big bets on stocks, bonds, currencies and commodities, has been in the news a little too frequently for its taste since the credit market turmoil began. It lost about 6 percent in its flagship AQR Absolute Return fund in November, putting the fund down nearly 12 percent through the first 11 months of the year.

In October, the $1.5 billion Global Asset Allocation fund lost 5 percent, putting it down 8 percent in the first 10 months of the year.

Like many hedge funds, AQR does not discuss returns publicly and only informs its clients about them.

The string of losses is giving even loyal investors reason to consider pulling out in the months ahead, according to several investors who have seen the performance numbers.

"They are taking on more risk without delivering the necessary returns, and I worry they may have lost their way in making money," said one investor, who asked not to be named.

AQR and other quant funds were hit hard in July and August as market troubles mounted.

Investors said the fund's quantitative strategies were off over 13 percent. They were soon relieved to see that much of the red ink had been reduced in the subsequent weeks.

AQR wasn't the only quant fund losing money this summer, industry sources said, noting that Renaissance Technologies, D.E. Shaw & Co. and others also took big hits.

But things are still not back to normal, said investors who were used to banking double-digit returns at AQR.

Even AQR acknowledged that times are tougher now.

"The returns on some of our products have been recently disappointing, but are within the bounds of what we would and do expect to happen from time to time," company spokesman Brian Maddox said.

For years, AQR and its founder, Clifford Asness, a Goldman Sachs alumnus who earned a PhD in finance at the University of Chicago, ranked among the most successful in the industry. Since founding AQR in 1998, Asness has been revered in the hedge fund industry and built up what investors called "masses of good will."

But recently some people have grumbled that the firm has become less transparent and information has become more difficult to obtain.

The firm said its executives are communicating regularly and appropriately with clients.

While AQR has suffered some redemptions, its past performance has wooed a lot of new business. At the start of 2007 its assets stood at $29 billion.

(Reporting by Svea Herbst-Bayliss; editing by John Wallace)