Since its 1957 launch, the S&P 500 has returned roughly 10% annually. Its average largest intra-year correction since 1980 was about 14%, while bear markets have come about every six years with average losses of 33%. Past performance does not predict future returns.
The article says returns were closer to 15% annually over the past decade. It also explains that index membership is periodically updated; Vanguard S&P 500 ETF (VOO) changes holdings through the index’s reconstitution and rebalancing. General Motors, U.S. Steel and Chrysler were among the top 10 holdings when the index launched.
