IBKR — S&P 500 index addition

Interactive Brokers Group (IBKR) entered the S&P 500 at the close on Aug 28, 2025, replacing Walgreens Boots Alliance. The recorded announcement came 6 calendar days before the effective close, on Aug 22, 2025. The company is classified in Financials in this dataset.

In the 30 calendar days leading into the effective close, IBKR moved +6.9%. The median 30-day run-up among the 25 S&P 500 entries with a recorded announcement and prices for that interval was +16.9%; this stock was 10.0 percentage points below that median. Measured from the effective close, IBKR returned 1W: +1.6% versus +0.3% for the 28-entry index median; 1M: +6.5% versus +2.2% for the 28-entry index median; 3M: +12.9% versus +5.2% for the 28-entry index median. These figures do not measure movement from the announcement price.

At 1M, it ranks 7th of 28 measured S&P 500 additions and beat the benchmark by 3.0 percentage points. At 3M, it ranks 9th of 28 measured S&P 500 additions and beat the benchmark by 6.0 percentage points. The 1Y window ends on Aug 28, 2026; a result needs a usable close. The other 6 Financials additions with a measured 1M return averaged -0.5%. This is historical context, not a projection.