(MONEY Magazine) – When we warned in our July issue that Fidelity Magellan, the country's largest mutual fund, was "too tied to tech," manager Jeffrey Vinik had 42% of assets (which totaled $42 billion) in technology stocks. But Vinik was undaunted. In the fund's semiannual report, dated Sept. 30, he praised several computer-related companies, including Micron Technology: "In my view, the stock is still relatively cheap." He also spoke favorably about Micron in a Nov. 6 interview with U.S. News and World Report that appeared in the magazine's Dec. 11 issue.

But at some point, Vinik changed his mind about the stock. Last month, the Washington Post reported that according to confidential trading data, from Sept. 30 to Nov. 20 Vinik sold 9.25 million of the fund's 11.77 million shares of Micron as well as nearly $1 billion worth of other tech favorites.

Citing company policy, Fidelity spokesman Scott Beyerl said neither he nor Vinik would comment on the fund's recent moves. Beyerl says that Vinik's Sept. 30 report, which was mailed to shareholders the week of Nov. 6, accurately reflected Vinik's views at the time. And he does not feel Fidelity was obliged to revise Vinik's comments to reflect a possible change of heart. "There has to be a cutoff date in these reports," he says.

The Securities and Exchange Commission is now looking at whether Vinik crossed a legal line by publicly sounding like a Micron buyer, then privately becoming a seller. Barry Barbash, director of the agency's investment management division, would not comment on this incident. He did say that a "if a manager made statements about a particular security and found out some new information, would he be prevented from selling? Probably not." But if he praised a stock while simultaneously selling it, Barbash says, "that could be a violation of securities laws."

Vinik has a history of shifting gears rapidly. Back in 1992, when he took over Magellan, he pumped up its stake in energy stocks to 19% almost overnight, then cut back to 4% in 1994. In early 1993 he had a tenth of the fund in utility stocks; today he has next to none. As we reported in our November 1995 issue, after gorging on tech, lately Vinik has favored economically sensitive businesses like industrial machinery and construction equipment. The lesson: When Vinik changes his mind, he acts fast. And don't expect him to tell you about it in advance.

Jeffrey Bernstein, 29, will take over as manager of $550 million Govett Smaller Companies (up 72.7% to Dec. 1) when Garrett Van Wagoner steps down Jan. 1. Bernstein, until recently an assistant fund manager at Bankers Trust, says he may add more mid-size stocks to the portfolio "because in a tough market they are more resilient than small stocks." Morningstar president Don Phillips suggests that existing Govett shareholders take some profits and that would-be investors steer clear of Govett. Among his concerns: Bernstein lacks an established track record, and the fund has 70% of its assets in technology, which is vulnerable to a correction.

One of the country's best small-company funds, PBHG Growth (up 46.3% to Dec. 1), will reopen to new investors as of Jan. 2. As the fund, managed by Gary Pilgrim, 55, neared its 10-year anniversary last month, it boasted a stunning average annual gain of 22.5%.

--Prashanta Misra and Jason Zweig