When it was first officially established on 3 March 1957, the S&P 500 (Index: SPX) had a total market capitalization of $172 billion. Over twenty-five years later, at the end of 1982, the market capitalization of the entire S&P 500 had grown to more than $1 trillion in 1982.

Now, nearly 36 years later, at least two of the 505 companies that currently compose the index have market caps that have reached values of $1 trillion or more: Apple Computer (Nasdaq: AAPL) and Amazon (Nasdaq: AMZN), neither of which existed in 1957 and only one of which existed in 1982.

Overall, the market capitalization of the entire S&P 500 stands at roughly $25.8 trillion through the end of August 2018. The following chart tracks the history of the index’ market valuation since it reached $1 trillion in value. We also have a chart showing the vertical axis on a logarithmic scale if you would prefer to see that version!

A third company, most popularly known as Google but officially called Alphabet (Nasdaq: Amazon (Nasdaq: GOOG and GOOGL), which also did not exist in either 1957 or in 1982, could also reach that lofty market valuation during 2018.