(MONEY Magazine) – The American Medical Association's $4 million purchase of the mutual fund group PRO Services Inc., now called AMA Advisers, has raised a debate about why the AMA did it -- and why it should not have. As for the first why, the answer is simple. ''The AMA will now own a business that makes a profit,'' says John E. Turner, chief investment officer for the $160 million fund group. The firm's five funds will remain open to any investors. But the why not question is tougher to resolve. Some health-care experts have suggested that the AMA, as a regulator of the medical profession, should not be in the mutual fund business, especially since at least two of AMA Advisers' funds specialize in medical technology companies. ''The AMA has people who issue advisories and lobby in Washington,'' points out Dr. Sidney Wolfe, director of the Public Citizen Health Research Group in Washington, D.C. ''Take an issue like: Should the government regulate medical devices? If the AMA is now linked financially to medical technology companies, its judgment could be impaired.'' Richard Pogue, senior vice president of the Investment Company Institute, a mutual fund trade group, dissents. ''A registered adviser has a responsibility to invest for the benefit of the stockholder. In this case, if the funds do well, the doctors do well. Our lawyers see no impropriety.'' AMA Advisers' open-end medical technology fund was up 22.7% for the year through July, compared with roughly 13% for the average equity fund.