MSTR will definitely NOT be joining the S&P500 this session. This is public information
Can you link a public source?
The official S&P Dow Jones Indices press release from August 25, 2025, announced that Interactive Brokers Group would be joining the S&P 500, with NO mention of MicroStrategy, which strongly signals its exclusion from being included.
Not that something can't change a the very last minute...but it doesn't look like it's going to happen.
One key for Strategy was that BTC kept its head about $98.8k which it has, so there may be a 'bit' of magic in the air, but at the time of the official S&P Dow Jones Indices press release it did not look promising for Strategy to be included...