Tech's increasing influence on the S&P 500

Technology stocks wield a significant influence on the cap-weighted S&P 500 index. Using the SPDR S&P 500 ETF Trust as a proxy, the information technology and communication services sectors had weights of more than 29% and 10%, respectively, at the end of 2021. Additionally, consumer discretionary includes Amazon.com and Tesla, which had 3.6% and 2.1% weightings, respectively.

Over the past several years, tech's weighting in the SPDR S&P 500 ETF has grown. IT made up more than 29% of the fund at the end of 2021, up from 16.2% five years earlier. Consumer discretionary also increased, standing at 12.5% vs. 9%. On the other side, financials, industrials, consumer staples, and energy all have seen their weighting fall by about 250 basis points to 485 points.

The S&P 500's top 10 holdings account for more than 25% of the fund. Apple and Microsoft have the biggest weights, at 6.8% and 6.2%, respectively. The two Alphabet share classes combined account for more than 4.1%.