United Capital Markets Holdings Inc. has stopped honoring refunds to investors in some of the firm's Horizon Strategy group hedge funds that invested in subprime-mortgage bonds, Bloomberg reported on its Web site on Tuesday.

The funds hold most of the firm's assets under management, which stood at about $619 million as of March, according to the report.

The company has had an unusually high number of redemption requests, including one from an investor who had put up about 25 percent of the funds' money, and it did not want to be a forced seller of securities, Bloomberg said, citing a spokesman.

The spokesman was not immediately available for comment.