‘I’d stay the course’: Vanguard’s Bogle

A long-term investment portfolio would still benefit from an allocation of 60 percent stocks to 40 percent bonds, Vanguard founder John "Jack" Bogle said Tuesday.

"I think the 60/40 still holds pretty well," he said. "I was troubled by it, say, two or three months ago when interest rates got to a frighteningly low level, meaning that the alternative to stocks – that is to say, bonds, which is the only alternative that I think is reasonable, really; the only income-producing alternative that's reasonable."

On CNBC's "Fast Money," Bogle acknowledged that it had appeared a tough trade to maintain.

"When you get to that position, it's hard to say, 'Take more money and put it into bonds,' because the returns are so low," he said, adding, "As everybody ought to know, today's bond yield is a terrific proxy, probably a 90 percent correlation, with its return over the next 10 years."

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Asked how investors should position their portfolios, Bogle was clear.

"First, I generally disapprove of changing your ratio in the middle of the stream. All these expectations in the marketplace are often kind of confusing and give you bad signals as an investor," he said. "I would just stay the course at this point."

Bogle also said that bond yields weren't necessarily at a turning point.

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"But certainly there is going to be a turn, and that's what the bond market, I think, is anticipating because we've had a really substantial increase," he said.

Bogle weighed in on emerging markets, noting that they were lower year to date while U.S. equities were up, for a 30 percentage-point spread.

Emerging markets were "a lot cheaper," he said, making for less skepticism at the moment.

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"In the longer run, I'd be more comfortable in emerging markets today, simply because the future returns will be relatively better than the market expects," Bogle added.

By CNBC's Bruno J. Navarro. Follow him on Twitter @Bruno_J_Navarro.

— CNBC's Patricia Martell contributed research to this report.

Trader disclosure: On Aug. 20, 2013, the following stocks and commodities mentioned or intended to be mentioned on CNBC's "Fast Money" were owned by the "Fast Money" traders: Joe Terranova is long GS; Joe Terranova is long MS; Joe Terranova is long VRTS; Joe Terranova is long OXY; Joe Terranova is long TRV; Joe Terranova is long EMC; Joe Terranova is long SJM; Joe Terranova is long TRIP; Joe Terranova is long SBUX; Joe Terranova is long HOS; Joe Terranova is long AXP; Joe Terranova is long PXD; Joe Terranova is long EOG; Joe Terranova is long CXO; Joe Terranova is long LTD; Joe Terranova is long CAT; Stephanie Link is long AAPL; Stephanie Link is long GS; Stephanie Link is long JPM; Stephanie Link is long WFC; Stephanie Link is long CSCO; Stephanie Link is long FB; Stephanie Link is long EBAY; Josh Brown is long XLU; Josh Brown is long XLF; Josh Brown is long BK; Stephen Weiss is long M; Stephen Weiss is long BAC; Stephen Weiss is long C.