Premium Subscriber Insights: SPR Exclusive Insights (Delayed Release)
Date: Sun, Sep 20, 2026 at 4:38 PM
Subject: September U.S. Market Outlook Update | Assessing the Impact of Triple Witching on Weekly Trend Signals
Dear SPR Premium Subscribers,
Following the confirmation of the U.S. stock market's transition into a correction phase last week, we expected this week's market to show a range-bound upward fluctuation, supported by bargain buying following the previous week's decline.
Based on the market's closing performance this week, the overall price movement remained within the range we had anticipated. However, an important distortion occurred toward the end of the week, particularly on Friday, September 18, which was a Triple Witching Day—the simultaneous expiration of stock options, index options, and index futures.
With approximately $6–7 trillion in options notional value expiring, the market experienced a sharp upward move during the final 10 minutes of trading. This significantly reduced the intraday decline and allowed the market to finish slightly higher, near the upper end of the week's trading range.
While this type of late-session movement can frequently occur around quarterly expiration dates, the context of this week's move is particularly important.
The market is currently in the early stages of a weekly trend transition into correction, rather than moving within an established and consistently rising trend. Therefore, the sharp movement during the final 10 minutes of Friday's session appears to have been significantly influenced by expiration-related supply-demand distortions rather than a fundamental change in the underlying weekly trend.
As a result, the weekly closing price has created a stronger appearance of a renewed upward trend, and the probability of an extension of the previous bullish trend toward late September or early October has increased based on the weekly closing data.
However, we believe the reliability of this signal is currently very low.
Once the expiration-related positioning has been cleared, market volatility could increase substantially, and the direction of the market could change rapidly. Because Friday's weekly close was heavily influenced by expiration-related flows during the final minutes of trading, the reliability of the week's overall buying-versus-selling supply-demand signal is currently limited.
For this reason, we recommend interpreting the current weekly trend signal with caution and placing greater emphasis on the market's behavior following the expiration.
1. Weekly Trend Outlook
Following last week's confirmed transition into a correction phase, the weekly market trend has continued to develop within the corrective range this week.
However, the Triple Witching expiration on Friday introduced a significant supply-demand distortion into the weekly closing data. As a result, the current weekly signal has shifted toward a scenario in which the previous upward trend could potentially extend again through late September to early October.
At this stage, however, the reliability of this scenario remains low.
We continue to expect next week's market to be characterized by overall selling pressure and a predominantly downward trend, consistent with the outlook presented in our previous email.
Even if the market rebounds, we expect such movements to be temporary or limited in magnitude. At the same time, as the expiration-related supply-demand distortion begins to normalize, volatility could increase, and a temporarily larger decline cannot be ruled out.
The most important point is that the market's actual behavior next week will help determine whether the current upward-extension signal has genuine underlying support or was primarily the result of temporary expiration-related flows.
Therefore, the reliability of the current weekly buying-versus-selling supply-demand signal cannot be considered sufficiently established yet.
We believe it is appropriate to maintain a conservative approach through at least next week.
Depending on how the market develops, there remains a meaningful possibility that the outlook could shift rapidly back toward a broader correction, particularly if the daily trend begins to weaken again.
For this reason, we recommend closely monitoring the daily market trend throughout next week.
2. Daily Market Outlook for Next Week
For the daily trend, we continue to expect the market to turn lower from the beginning of next week, with downward pressure becoming more dominant.
As discussed approximately two weeks ago, we previously identified the possibility of a stronger downward move emerging around this period. At present, there has been no meaningful change to that outlook, and we continue to expect the stronger decline to begin around the start of next week.
However, the expiration-related supply-demand distortion on Friday has also affected the daily trend signal. As a result, the expected duration and magnitude of the decline may be somewhat more moderate than previously anticipated.
That said, because the reliability of Friday's supply-demand data is currently low, this expectation could change rapidly depending on the actual market behavior at the beginning of next week.
One particularly important period to watch will be Thursday through Friday.
The magnitude and quality of any rebound during this period could have a significant impact on whether the broader weekly outlook changes again.
In other words, next week's market movement will be important not only for determining the direction of the daily trend, but also for validating whether the recent upward shift in the weekly signal represents a genuine improvement in underlying buying demand or merely a temporary effect caused by expiration-related positioning.
For now, we recommend maintaining a conservative approach and avoiding overinterpretation of this week's late-session rebound until the market establishes a more reliable supply-demand direction after the expiration.
We will continue to closely monitor the daily and weekly trends and will provide an updated outlook if any significant change develops.
If you have any questions regarding our analysis, please feel free to contact us at any time.
Thank you.
SPRㅣ Stock Pretiming Report team.
All forecasts are probabilistic and subject to change as market conditions evolve. Investment decisions remain solely the responsibility of each investor.)
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