Briefly

Microsoft Chairman Bill Gates plans to invest $100 million in Mario Gabelli’s $26-billion mutual fund management business, helping finance the firm’s push into Europe. Gates’ personal investment company, Cascade Investment, agreed to buy a 10-year convertible note in Gabelli Asset Management Inc. (ticker symbol: GBL), Gabelli said. If the note is converted into stock, Cascade will own 6% of the money management firm, whose stock rose $1.35 on Monday to $45.13. . . . Web brokerage E-Trade Group Inc. (ET) plans to close its ailing electronic commerce-focused mutual fund, the latest casualty in the shrinking Internet mutual fund sector. E-Trade’s E-Commerce Index Fund, designed to track the Goldman Sachs E-Commerce index, has lost 59.6% over the last year. The fund’s $30 million in assets will be folded into the $47-million E-Trade Technology Index portfolio, pending shareholder approval.