have their money invested by professionals. And because mutual funds hold diversified groups of stocks, they shelter investors somewhat from the sharp swings that can occur in the value of individual shares. There are dozens of kinds of mutual funds, each designed to meet the needs and preferences of different kinds of investors. Some funds seek to realize current income, while others aim for long-term capital appreciation. Some invest conservatively, while others take bigger chances in hopes of realizing greater gains. Some deal only with stocks of specific industries or stocks of foreign companies, and others pursue varying market strategies. Overall, the number of funds jumped from 524 in 1980 to 7,300 by late 1998. Attracted by healthy returns and the wide array of choices, Americans invested substantial sums in mutual funds during the 1980s and 1990s. At the end of the 1990s, they held $5.4 trillion in mutual funds, and the portion of U.S. households holding mutual fund shares had increased to 37 percent in 1997 from 6 percent in 1979.