The U.S stock market trounced returns on a diverse group of 13 indexes tracking major asset classes in the five years ended March 31, 2021. U.S. large-company stocks returned twice as much as foreign stocks and 10 times as much as intermediate-term bonds. U.S. stocks are the main growth engine of a prudently designed, broadly-diversified portfolio which makes the extraordinary outperformance by stocks fantastic news for U. S. retirement inv..