Walmart Walmart's (NYSE: WMT) stockholders are also looking back fondly on 2020, with a 21% price gain that crushed the S&P 500's 14% increase. The top line was strong during fiscal 2020 (ended Aug. 30) with same-store sales (comps) increasing by 9% when excluding foreign currency exchange translations and changes in gasoline prices. While COVID-19 helped Costco's performance -- since it remained open while governments forced others to shut their doors -- this wasn't entirely driven by increased buying due to the virus.