This is turning out to be a good year for index funds. Through April 30, both equity and fixed-income index funds have captured close to 75 cents of every one dollar investors have invested in mutual funds, according to Lipper of New York.

Of the $32.2 billion of new money that flowed into mutual funds year-to-date through April 30, more than $7.5 billion has flowed into index funds, according to Lipper. That means index funds have so far this year snared 23 percent of all assets, said Don Cassidy, senior research analyst with Lipper.

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