Investing through index funds is more popular than ever, so why is it becoming controversial? Index fund investing has had a huge effect on the stock market.

The second critique, that the leading index-fund providers have become too dominant, is more substantial. Unlike the previous assertion, it is not old wine repackaged in a new bottle.

No actively managed stock or bond funds outperformed the market convincingly and regularly over the last five years. Index funds have generally been better.