Key PointsWarren Buffett recommends that non-professional investors periodically buy shares of an S&P 500 index fund. The Vanguard S&P 500 ETF provides cheap and easy exposure to the most influential stocks in the world. And he has consistently given the same advice: Buy an index fund that tracks the S&P 500 (SNPINDEX: ^GSPC)"In my view, for most people, the best thing to do is to own the S&P 500 index fund," Buffett told attendees at Berkshire's annual meeting in 2021. The pros and cons of the Vanguard S&P 500 ETFThe Vanguard S&P 500 ETF measures the performance of the S&P 500, which itself tracks 500 large U.S. companies. That means most professional money managers would have been better off buying an S&P 500 index fund.