The single most important financial measure of the United States, the Standard & Poor’s 500 index, closed 2021 less than 1% from its all-time high reached only two days ago, and with a spectacular calendar-year return of 26.9%. The Standard & Poor’s 500 stock index closed 2021 at 4766.18. The index lost -0.26% from Thursday and gained +0.85% from last Friday. The S&P 500 is up +72.21% from the March 23, 2020, bear market low..