New York CNN Business  — 

John Bogle, who created the first index fund in 1975 and founded The Vanguard Group, died Wednesday at the age of 89.

Bogle is legend in the investing world for inventing a low-cost way for individuals to invest in the broad market, and advocating for their interests.

“Jack Bogle made an impact on not only the entire investment industry, but more importantly, on the lives of countless individuals saving for their futures or their children’s futures,” Vanguard CEO Tim Buckley said in a statement. “He was a tremendously intelligent, driven and talented visionary whose ideas completely changed the way we invest. We are honored to continue his legacy of giving every investor ‘a fair shake.’”

Vanguard is now the largest investment firm in the world. And at the end of December, index funds had more than $6 trillion in assets under management, according to Morningstar. One of the largest is the Vanguard 500 Index Fund with more than $440 billion. All Vanguard index funds combined account for more than 70% of the firm’s nearly $5 trillion in assets, according to the company.

Bogle was revered for his steadfast commitment to the best interest of the investor.

In a remembrance, Christine Benz, Morningstar’s director of personal finance, said, “You were the conscience of the financial services industry and leave an awesome legacy of genuinely improving investors’ lives.”

Dennis Kelleher, president of Better Markets, a nonprofit promoting the public interest in financial markets, put it this way: “Freeing everyday Americans from relentless and usually empty broker sales pitches, [Bogle] enabled tens of millions of people to get the benefit of compound returns while avoiding the tyranny of fees.”

Bogle’s interest in investing started young. As an economics major, he wrote his senior thesis on mutual funds at Princeton, from which he graduated cum laude, according to Vanguard. That thesis got the attention of Walter Morgan, a lion in the mutual fund industry, who hired him in 1951 to work at the Wellington Fund, which Morgan had founded.

He left after a management dispute in 1974 and started Vanguard.

In addition to his day job, Bogle also served as chairman of the board of governors at the Investment Company Institute and chaired what became FINRA, which regulates broker-dealers.

After retiring from Vanguard in 1996, Bogle continued to write and speak on financial markets and investors up until his death.

In November, Bogle sounded a warning, expressing concern that index funds may eventually own half of all US stocks. “I do not believe that such concentration would serve the national interest,” he wrote in the Wall Street Journal.

He published 12 books. His latest, Stay the Course: The Story of Vanguard and the Index Revolution, came out just last month.

With his wife Eve Sherrerd, whom he married in 1956, Bogle had six children, 12 grandchildren and six great-grandchildren.