蜜芽传媒

Warren Buffett is the world鈥檚 most successful investor. In a letter he wrote to his wife, advising her how to invest after he dies, he offers some clear advice: put almost everything into 鈥渁 very low-cost S&P 500 index fund鈥�. Index funds passively track the market as a whole by buying a little of everything, rather than trying to beat the market with clever stock picks 鈥� the kind of clever stock picks that Warren Buffett himself has been making for more than half a century. Index funds now seem completely natural. But as recently as 1976 they didn鈥檛 exist. And, as Tim Harford explains, they have become very important indeed 鈥� and not only to Mrs Buffett.

Editors: Richard Knight and Richard Vadon
Producer: Ben Crighton

(Image: Market graphs, Credit: Shutterstock)