Want a smoother ride? Bespoke presents the 40 least volatile S&P 500 names, stocks with the smallest difference between their high and low prices over the last decade. Wal-Mart (WMT) has been the least volatile stock, with a 10-year high-low spread of just 54%. Only six other S&P 500 stocks have spreads below 100%: KMB, PGN, JNJ, SCG, KO. ED.