Few investment books make it to a ninth edition. One that’s beat the odds is Burton Malkiel’s A Random Walk Down Wall Street. Released anew earlier this year, Random Walk is the original treatise on indexing and its allure as an investment strategy. The first edition was released more than 30 years ago, but the message has withstood the test of time for the simple reason that it works. In short, it’s hard to beat the market over time, and if you can’t beat ’em, join ’em. The argument is now in middle age, but the inherent wisdom is as relevant as ever. With that in mind, we recently interviewed Malkiel for the May issue of WM and asked him what’s new in the 9th edition and how the update compares with the original.