Index funds: How Jack Bogle's innovation changed investing forever

The creation of the index fund in 1975 revolutionized investing, lowering costs for millions of ordinary investors.

Their inventor John Bogle died on Jan. 16 at the age of 89.

Bogle took a complex universe of thousands of stocks and reduced it to a simple, singular entity, the index fund. Through index funds, investing in the stock market became easy, and one could do so at low cost while minimizing risk.

Practitioners and academics have researched the drivers and consequences of index fund investing – myself included. Here is some of what we know.

Investing before index funds

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