Investors Raise Stake in Readicare : * Stock: Chicago group now owns 10.3% of Irvine workers’ compensation claim specialist but says it won’t try to take control.

A Chicago investment group has increased its stake in Readicare Inc. to 10.3% but says it has no plans to seek control of the operator of outpatient medical centers specializing in workers’ compensation claims.

Harris Associates L.P., an investment advisory firm and mutual funds manager, has nearly doubled its stake in Irvine-based Readicare by acquiring 417,800 shares of the company’s stock, boosting its total holdings to 852,000 shares. The company previously owned 5.3% of Readicare.

Harris Associates executives said Thursday that the group’s investment in Readicare has a current value of $5.3 million.

Readicare stock closed Thursday at $6.375, up 25 cents a share in American Stock Exchange trading.

“This is part of our portfolio holding, and there’s absolutely no plans to take over the company,” said Victor Morgan Stern), president of Harris Associates. “(The 10.3% stake at Readicare) is getting toward as high a position as we want.”

Readicare executives could not be reached for comment Thursday.

Harris began purchasing Readicare shares in mid-January as part of a plan to invest in companies specializing in helping companies control health-care costs, said Ralph Wanger, president of Acorn Fund, a mutual fund operated by Harris.

Harris continued its Readicare stock purchases until early February, according to a filing with the Securities and Exchange Commission.

Wanger said Readicare and other companies that specialize in curbing workers’ compensation expenses should be in increasing demand in the 1990s as U.S. companies grapple to find ways to limit health care costs.

“We think they’re going to be growing very rapidly in the future,” he said. “They’re building new rehabilitation centers. They’re going to help companies save money in workers’ compensation (costs), and California certainly has a major problem in workers’ compensation.”

Separately, Readicare announced that Mark S. Tanaka has resigned as a board member. Tanaka, who had served as a director since 1986, said he wants to spend more time with clients of the Sacramento health care consulting firm he owns.

Readicare, which has four directors, said it has no plans to replace Tanaka.