Warren Buffett’s blunt advice for a trustee in 2013 is still being treated like a live roadmap: put 10% of the cash in short-term government bonds and 90% in a very low-cost S&P 500 index fund. He even suggested Vanguard’s fund, a nod that now gets translated into the Vanguard S&P 500 ETF for investors looking for a simple, long-haul holding.
That recommendation is getting fresh attention because the math is hard to ignore. The Vanguard S&P 500 ETF carries a 0.03% expense ratio, so even small cost differences can matter over decades. On a $1 million balance, a fund charging 0.03% would cost about $300 a year, while a higher-fee fund would take a larger bite every year after year, and that gap compounds over 40 years.
Buffett’s point was never about timing the market. It was about owning a cheap slice of the biggest U.S. companies and letting time do the work. The S&P 500 is market cap-weighted, which means the largest companies carry the most influence, and that structure has made the index more concentrated than many casual investors realize. The top 10 holdings now make up nearly 40% of the index, and the tech sector accounts for 40% of it. For investors who want broad exposure, that still works. For anyone assuming they are buying a perfectly balanced basket, it does not.
That concentration is the part that keeps the recommendation from sounding like a slogan. The S&P 500 can be volatile, and 20%-plus pullbacks are not unusual. If the tech rally reverses, the index could feel the hit faster than an equal-weight S&P 500 fund, because so much of the benchmark’s weight sits in a handful of names. Buffett’s advice holds up as a low-cost default, but it is not a promise that the ride will be smooth.
Even so, the case for patient investors has not changed much. The strategy is designed to be held for at least 10 years, and automatic monthly investing can help the account grow faster over the next 40 years. The logic is simple enough for Buffett to have put it in one sentence, and durable enough that investors searching for index funds still end up back at the same place: own the market cheaply, stay in it long enough, and let the years do the heavy lifting.
