They've got a lot of competition these days from so-called alternatives like ETFs and other products, many of which have been quickly lapping up new assets in recent years. But mutual funds' all-out dominance of the vast U.S. investment universe remains unchallenged. In fact, they account for a full 93 percent of investment assets in the U.S., according to the Investment Company Institute. Meanwhile, their share of total U.S. household financial assets is even higher today than it was just 10 years ago, up to 23 percent in 2007 from 15 percent in 1997.

INVESTMENT COMPANY ASSETS, IN BILLIONS OF DOLLARS

Year Mutual funds Closed-end funds ETFs UITs Total
1996 $3,526 $147 $2 $72 $3,747
1997 4,468 152 7 85 4,712
1998 5,525 156 16 94 5,791
1999 6,846 147 34 92 7,119
2000 6,965 143 66 74 7,248
2001 6,975 141 83 49 7,248
2002 6,390 159 102 36 6,687
2003 7,414 214 151 36 7,815
2004 8,107 254 228 37 8,626
2005 8,905 276 301 41 9,523
2006 10,414 298 423 50 11,185
2007 12,021 315 608 53 12,997
Source: Investment Company Institute