Who invented the index fund? Most investors would guess it was Vanguard founder John Bogle. Bogle did launch the first publicly available index fund in 1976. After being derided as “Bogle’s folly,” it went on to become today’s Vanguard 500 Index Fund, a name nearly synonymous with indexing.

So it may come as a surprise to learn that Bogle did not actually invent the index fund. That credit goes to three gentlemen who created the first institutional index funds in the early 1970s: Dimensional Fund Advisor board member John “Mac” McQuown, co-founder and Executive Chairman David Booth, and co-founder Rex Sinquefield.

In this brief video, Booth reflects on the evolution of indexing and evidence-based investing, which led to Dimensional’s own value-added approach. “The basic idea of indexing has been an overwhelming success,” says Booth, but “Dimensional built the firm on the idea that we could do better.”

Dave Goetsch – The name may not be instantly familiar, but you’ve probably heard of the CBS sitcom he produces: “The Big Bang Theory.” Like his show, Goetsch’s personal investing has had its share of twists and turns. Reflecting on how he felt back in 2009, he says, “When the market went down, I went down with it—sinking into a depression, knowing there was nothing I could do.”

Fortunately, between then and now, he discovered an evidence-based investment approach. Armed with the durable philosophy he lacked at the time, Goetsch has leveraged his past trauma as a learning experience, and now feels better prepared for future downturns.

These days, Goetsch is proud to help spread the evidence-based investing word along with us. “I changed because I learned that there was a different way to think about investing. … The return I’m talking about is how I feel every day. I worry less—not just about the future, but also about the present. Of course, I know that there are no guarantees when it comes to investing, but I feel like I’m going to be okay. I have a plan.”

To read Dave’s observations in his own words, click here: “Now and Then.”

We encourage investors to mostly look past annual returns and keep their eyes on the market’s long-term performance. But it can be helpful to consider annual reports too, as long as we do so within this greater perspective.

Speaking of perspective, there’s also global versus domestic viewpoints. The Dimensional Fund Advisors chart below, ranking 2017 return sources, illustrates why we continue to believe it’s best to globally diversify your risks and expected returns around the world. While the U.S. S&P 500 performed nicely in 2017, returning just under 22 percent, notice how many international markets did even better, with emerging markets significantly outpacing all the rest.

Of course, from one year to the next, the reverse can easily be true. So, to quote Nick Murray, an industry thought leader:

“We will never own enough of any one idea to make a killing in it. We will never own enough of any one idea to risk being killed by it.”

This is what diversification is for.