SPX returns around options expiration show almost no difference
OPEX week is the week of monthly options expiration (third Friday of the month). This week it's Friday, August 21, 2026. We backtested every monthly OPEX week on the S&P 500 from September 15, 2006 through July 17, 2026. That covers 239 weeks.
Across 239 monthly expirations, SPX closed the week higher 137 times, or 57.3% of the time. The average return was +0.11% and the median was +0.32%. By comparison, the other 773 Friday-ending weeks closed higher 57.2% of the time and averaged +0.20%, about a tenth of a percentage point better.
| Group | Weeks | Closed higher | Average | Median |
|---|---|---|---|---|
| OPEX weeks | 239 | ▲57.3% / ▼42.7% | +0.11% | +0.32% |
| Other Friday-ending weeks | 773 | ▲57.2% / ▼42.8% | +0.20% | +0.31% |
| Quad-witching OPEX weeks | 80 | ▲63.7% / ▼36.3% | +0.22% | +0.69% |
| Regular monthly OPEX weeks | 159 | ▲54.1% / ▼45.9% | +0.05% | +0.19% |
Quad witching is the only category that clearly stands out from a normal week. It closed higher in 51 of 80 weeks, or 63.7% of the time, with a median return of +0.69%. Regular monthly OPEX weeks were higher in 86 of 159 cases (54.1%) and had a median return of just +0.19%.
October stands out clearly: 17 of 20 OPEX weeks closed higher. January sits at the other extreme, with only 7 of 20 closing higher. Each bar shows the average week return for that month's expiration.
| Month | Weeks | Closed higher | Average | Median |
|---|---|---|---|---|
| January | 20 | ▲35.0% / ▼65.0% | -0.53% | -0.29% |
| February | 20 | ▲60.0% / ▼40.0% | +0.41% | +0.84% |
| March (quad) | 20 | ▲65.0% / ▼35.0% | +0.16% | +0.74% |
| April | 20 | ▲55.0% / ▼45.0% | +0.62% | +0.56% |
| May | 20 | ▲45.0% / ▼55.0% | -0.31% | -0.18% |
| June (quad) | 20 | ▲65.0% / ▼35.0% | -0.06% | +0.33% |
| July | 20 | ▲60.0% / ▼40.0% | +0.31% | +0.49% |
| August | 19 | ▲42.1% / ▼57.9% | -0.46% | -0.53% |
| September (quad) | 20 | ▲65.0% / ▼35.0% | +0.74% | +1.03% |
| October | 20 | ▲85.0% / ▼15.0% | +0.79% | +0.86% |
| November | 20 | ▲50.0% / ▼50.0% | -0.45% | -0.04% |
| December (quad) | 20 | ▲60.0% / ▼40.0% | +0.02% | +0.60% |
The strongest OPEX week was the one ending July 17, 2009, which returned +6.97%. The weakest was the week ending March 20, 2020, which fell -14.98% during the Covid crash. The longest winning streak was five consecutive higher OPEX weeks, ending on October 19, 2018. The longest losing streak was six consecutive lower weeks, ending on September 16, 2022.
Six expirations fell on a Thursday because the third Friday was a market holiday (either Good Friday or Juneteenth). Those dates were March 20, 2008; April 17, 2014; April 18, 2019; April 14, 2022; April 17, 2025; and June 18, 2026.
| OPEX Friday | Type | Week |
|---|---|---|
| Jul 17, 2009 | Monthly | +6.97% |
| Mar 18, 2022 | Quad | +6.16% |
| Sep 16, 2011 | Quad | +5.35% |
| May 16, 2025 | Monthly | +5.27% |
| Oct 21, 2022 | Monthly | +4.74% |
| OPEX Friday | Type | Week |
|---|---|---|
| Mar 20, 2020 | Quad | -14.98% |
| Nov 21, 2008 | Monthly | -8.39% |
| Dec 21, 2018 | Quad | -7.05% |
| Feb 20, 2009 | Monthly | -6.87% |
| Jun 17, 2022 | Quad | -5.79% |
Monthly expiration week on SPX is the same as any other week, with a slightly lower average return. Quad witching is the one clear exception worth noting: those 80 weeks closed higher 63.7% of the time, with a median of +0.69%, against 54.1% and +0.19% for regular monthly OPEX.
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