Agree with most of it except the bolded. The number of shares to be bought remains the same, what changes is the price they are paying for each share.
@vikings123 thanks for correcting my post. I'd forgotten some of the gory details from my lengthy July 6, 2020 post, "
S&P 500 Future TSLA Addition Analysis" about "Mean S&P 500 Float-Adjusted Market Cap", etc. I wrote it after investing several hours studying S&P website documents.
"However, S&P 500 rules state that "
Weighting. Each index is weighted by float-adjusted market capitalization."
TSLA: Shares Outstanding = 185.48M; Float = 147.62M; % Held by Insiders = 20.51%; % Held by Institutions = 57.93%.
Float-adjusted market capitalization = 147,620,000 x $1,371.58 = $202,472,000,000 ($202B). ("Float-adjusted" removes the shares held by insiders like Elon that are presumably mostly not for sale.)
According to S&P, Mean S&P 500 Float-adjusted Market Cap Weighted today is $53,391.96M x 505 Constituents = $26,962.94B. TSLA would be 0.75% of this, which is its float-adjusted market cap as of 7/6/20 close.
S&P also states there is over USD 4.6 trillion indexed to the S&P 500. $4,600B x 0.75% = $34.5B worth of TSLA stock the indexers will be forced to buy. At today's close, that represents 25,153,472 shares or 17% of the "float". Will that be enough to cause an extreme spike up in the price when TSLA is added? By contrast, today's volume was 20.5M and the average is 14.2M."
"When TSLA is added to S&P 500 it will also get added to the "S&P 500 Top 50" at the next annual reconstitution after the close of the third Friday in June 2021, using a reference date of the last business day of May 2021."
Note those were all pre-split numbers.
I also predicted this on July 6th which came true 2 months later:
"Still, I will go out on a limb and predict that $TSLA will exceed $2,000/share within a week of being added to the S&P 500 on 9/28/2020. ... Do I get to revise my prediction upwards to $2,500?
"
https://www.spglobal.com/spdji/en/d...odology-sp-us-indices.pdf?force_download=true