Wal-Mart has 3.81 billion shares outstanding, Apple at 900 million. So fluctuations of a dollar on the price of Wal-Marts stock will raise or lower the market cap 3.81 billion dollars. I like Enterprise Value (EV) as a better gauge, and Wal-Mart still has them by a good 20%. "Enterprise value is calculated as market cap plus debt, minority interest and preferred shares, minus total cash and cash equivalents."