A person invested in the S&P500 index fund, he found:

1.Tesla to join S&P 500, spark epic index fund trade, by Noel Randewich in Reuter, 16 November 2020

2. Tesla shares surge to new high on S&P 500 inclusion by Michael Mackenzie, David Carnevali and Eric Platt in the Financial Times of the 18th of December 2020

Therefore, he believes that Tesla's pricing is too high and extremely risky, and its price may plummet in the near future and may damage the returns of its index funds. Due to his limited professional knowledge, he would like to know your suggestions and opinions, especially how you will include Tesla in the S&P500 index and how it will affect the performance of the S&P500 index fund he owns.

Question: Explain how to calculate the S&P 500 index from its constituent securities