Most investors, knowing that the stock market crashed in October 1987, probably would say that the summer of 1987 was not a good time to invest. Yet 90 percent of mutual funds have increased in value in the three years from mid-1987 to mid-1990, says Mutual Fund Forecaster, a monthly newsletter based in Fort Lauderdale, Fla. "The fact of the matter is that funds have performed extremely well over this three-year period," it says. The top-performing funds had spectacular gains since then, it says. G.T. Japan Growth increased by 141 percent, while Gabelli Growth gained 86 percent. Growth funds liked Janus and Calvert-Ariel Growth grew by 70 percent. Two funds that specialize in telecommunications stocks -- Flag-Telephone Income and Fidelity Select Telecommunications -- gained 75 percent and 72 percent, respectively. The only category of funds that did poorly during the period were gold stock funds, which were hurt by the decline in gold prices since 1987.