Does joining the S&P 500 pay?
Across 28 S&P 500 additions, measured from the effective-date close. In the 30 days before the close, the average stock moved +20.5%.
Reading the S&P 500 results
For 28 recorded one-month results, this index's additions averaged +0.5%, while the median was +2.2%. By comparison, Nasdaq-100 additions averaged -2.2% and had a +0.8% median across 14 recorded one-month returns. These are different stocks and periods, not a controlled test. S&P 500 membership is committee-selected and closely followed by large passive funds. Anticipation before the effective close, rather than buying after it, may matter when reading these return windows; the table does not isolate the effect of index-fund trading.
Returns by holding period
Average and median return at each window, and the share that finished higher
| Window after close | Sample | Average | Median | Finished higher | Avg vs index |
|---|---|---|---|---|---|
| 1W | 28 | +0.2% | +0.3% | 50% | 0.0% |
| 1M | 28 | +0.5% | +2.2% | 54% | -0.1% |
| 3M | 28 | +7.3% | +5.2% | 57% | +2.7% |
| 6M | 28 | +14.8% | +13.4% | 64% | +7.1% |
| 1Y | 24 | +27.6% | +11.6% | 63% | +11.3% |
| Entries in the register | 28 | Samples shrink at longer windows because recent entries haven't reached them yet | |||
Best and worst one-year results
The two ends of the register at the 1Y window