A Random Walk Down Wall Street, written by Burton Gordon Malkiel, a Princeton University economist, is a book on the subject of stock markets which popularized the random walk hypothesis. Malkiel argues that asset prices typically exhibit signs of a random walk and that one cannot consistently outperform market averages. The book is frequently cited by those in favor of the efficient-market hypothesis. As of 2020, there have been twelve editions and over 1.5 million copies sold. A practical popularization is The Random Walk Guide to Investing: Ten Rules for Financial Success.