Jack Bogle, the legendary founder of Vanguard Group, offers four rules to investing success: it’s all about keeping it simple.

Bogle used to have a really basic portfolio that followed an asset allocation known as the 60-40 rule — 60 percent in a U.S. stock index fund and 40 percent in a U.S. bond index fund. But he recently shifted his strategy by a hair: He's now at 50/50, which makes his portfolio slightly more conservative, CNBC reports

"I just like the idea of having an anchor to the windward," Bogle, who is 86, told CNBC. "I'm not so much worried about having my estate grow."

Here are the 4 secrets he shared with CNBC:

1. Don't rebalance your portfolio

Many investment advisers sell their services in part based on “rebalancing,” or selling your winners to return your portfolio to its asset allocation. Research shows you will reduce your risk of a big loss in the short term in your portfolio with regular rebalancing.

However, there are possible fees, taxes and other pitfalls. "If you want to do it, once a year is probably enough," he said.

2. Don't invest overseas

Bogle keeps his portfolio entirely in U.S. markets. "We have the best investor protections and legal institutions," he said.

3. 'Diversification' means bonds — and bonds only

Bogle uses bonds to offset equity risk in his portfolio. He boosts the bond allocation as he ages, because he wants to reduce the risk of a sudden drop in value.

4. 'Simple' portfolio choices prevents worrying

The genius of Bogle's portfolio, for him, is its simplicity. It's easy for him to track and understand.

Terry Savage, a nationally recognized expert on personal finance, the economy and markets, agrees with Bogle.

“There is a huge financial services industry dedicated to helping you manage your money. But the real secrets of successful investing and wealth creation are so simple that you shouldn't be overwhelmed by all the choices being offered,” she writes in the Huffington Post.

“Instead, start with one small principle:The secret of financial success is to make your money work for you, as hard as you work for it, over time!”

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