(CNBC) -- Warren Buffett, 87, told fund manager Mark Yusko he will not do another bet that a simple S&P 500 index fund will beat a basket of hedge funds.
The "Oracle of Omaha" cited his age as reason not to go forward with a second 10-year wager against the hedge fund industry, in an email to Yusko Tuesday. Buffett is on track to beat the original wager this year by a blowout.
Wrote Buffett to Yusko:
"I think the Protege bet proved the point and has stimulated a re-evaluation of professional management. If I were to do another ten-year bet — and I regard that as the reasonable term for measurement — that would take me to 97 and not at the best point to write and talk about the results. There's no doubt in my mind, however, that the S&P 500 will do better than the great majority of professional managers achieve for their clients after fees."
Buffett told CNBC's Becky Quick last week that he was willing to do another bet on active versus passive as long as anybody wants to put up "a significant percentage of their net worth" on the wager.
Morgan Creek Capital's founder and chief investment officer, Mark Yusko, accepted Buffett's offer on the same day. His firm manages $1.8 billion.
The bet with Buffett "is definitely not happening. I'm surprised because he came on CNBC offering another bet. After talking to him last week I thought there was a good chance," said Yusko in a phone interview Wednesday.
But the Oracle must have changed his mind.
"I'm disappointed because his involvement would have kept the public interest on this very important topic [active versus passive] at the highest level," said Yusko.
The investor explained why he was so adamant over his advocacy for hedge funds last week.
"It's an important time in terms of the market cycle. I think it's important to be aware about the propensity of investors to chase hot returns at the peak of the cycle. It is a better time to get hedged," Yusko said on Oct. 3.
Even though Buffett said no to Yusko, the investor is hopeful perhaps another person will take the wager.
A decade ago, Buffett made a million-dollar bet with Seides, a former co-manager of Protege Partners, that the S&P 500 will beat a basket of fund of hedge funds over the next 10 years, ending this year. The Berkshire Hathaway chairman and CEO will likely win that bet by a large margin.
Seides conceded he lost the bet earlier this year.
Buffett still won the original wager even after a vicious bear market occurred as a result of the housing crisis. The new bull market began in March 2009.
Hedge funds lost out to simple index funds as an economic recovery and extraordinary Federal Reserve stimulus lifted the majority of stocks and assets during this latest run.
The S&P 500 "will absolutely kill every one of the fund of funds," Buffett said on CNBC's "Squawk Box" last week. "Passive investment in aggregate is going to beat active investment because of fees."
Berkshire Hathaway did not immediately respond to a request for comment.