Day of Week Trading Strategy – The “Twisted DOW” That Outperforms the Classic Approach
Larry Williams popularized the idea of trading only on specific days of the week. It makes intuitive sense – certain days tend to perform better than others. But what if I told you the classic approach has a serious flaw, and there is a much more stable way to use day-of-week filtering in your breakout strategies?
In this episode, I share what I call the “Twisted DOW” – a day of week trading strategy that flips the conventional wisdom on its head. Instead of cherry-picking the best days, we exclude the worst ones. The difference in stability and robustness is remarkable, and the numbers prove it.
The Classic Day of Week Approach and Its Problem
The traditional day of week trading strategy is straightforward. You analyze your strategy’s performance across each day of the week – Monday through Friday – and then you only trade on the days that show the best results. If Wednesday and Thursday are your top performers, you restrict your strategy to those two days only.
This is a concept Larry Williams introduced, and on the surface, it looks brilliant. Why trade on days that drag down your performance when you can just focus on the winners?
The problem is stability. When you select only the best-performing days, you are optimizing aggressively. You are fitting to historical noise. Those “best days” can shift over time, and suddenly the days you selected are no longer the top performers. Your beautifully optimized strategy falls apart in live trading because the edge was never in those specific days – it was just historical coincidence.
The Twist – Exclude the Worst Instead of Picking the Best
Here is the twist that changes everything. Instead of asking “which days should I trade?”, ask “which days should I definitely NOT trade?”
This is a fundamentally different approach. You are not trying to find the optimal days. You are trying to remove the clearly bad ones. The distinction matters enormously for robustness. A day that consistently loses money is a much more stable signal than a day that happens to be the top performer right now. Bad days tend to stay bad. Best days rotate.
Think of it like this: you cannot always predict which restaurant will be the best in town, but you can reliably identify the ones with health code violations. Avoiding the worst is more stable than chasing the best. This principle applies directly to breakout trading strategy design.
Real Results – The Numbers Behind the Twisted DOW
Let me show you what this looks like with real data. I took a strategy – the LOD (Low of Day) breakout strategy from a previous video – and analyzed its day-of-week performance.
The baseline strategy had an average trade of $59. Decent, but not spectacular. When I looked at the daily breakdown, Monday and Tuesday stood out as consistently weak performers. They were dragging down the overall numbers.
Here is where the Twisted DOW kicks in. Instead of trying to find the perfect combination of best days, I simply excluded Monday and Tuesday – the two worst performers. The result?
Average trade jumped from $59 to $104. That is a 76% improvement in average trade just by removing the weakest days. And the beauty of this approach is that it is far more stable than the classic method because we are not optimizing for the best – we are simply cutting the worst.
Why Exclusion Is More Robust Than Selection
Let me explain why this matters so much for anyone building algorithmic breakout strategies.
Fewer Optimization Decisions
When you pick the best days, you are making an aggressive optimization choice. With five trading days, selecting the best two or three creates many possible combinations. Each combination is a potential overfitting trap. When you exclude the worst one or two days, you are making a much simpler, more conservative decision that is less likely to be curve-fitted.
Negative Edges Are Stickier
Markets have structural reasons why certain days underperform. Monday often carries weekend gap risk and uncertain positioning. These structural factors tend to persist over time. A day that is consistently bad has a reason behind it. A day that is the “best” might just be random. This is the same principle behind filtering out bad trades – removing what clearly does not work is more stable than trying to isolate perfection.
Better Sample Size
By excluding only one or two days instead of selecting only two or three, you keep more trades in your sample. More trades means more statistical significance. More significance means more confidence that your edge is real, not noise. This aligns perfectly with the validation principles we use to confirm strategy robustness.
Always Validate on Other Indexes
One critical step that many traders skip: after applying any filter – including the Twisted DOW – you must validate it on other index markets. If excluding Monday and Tuesday improves your strategy on the E-mini S&P 500, does it also help on the E-mini NASDAQ? What about Russell 2000?
If the day-of-week exclusion improves performance across multiple correlated markets, you have much stronger evidence that the filter is capturing a real market phenomenon rather than noise specific to one instrument. This cross-validation step is non-negotiable in our strategy development process.
We do not just want strategies that backtest well on one market. We want strategies that reflect genuine market dynamics. The Twisted DOW tends to pass this cross-validation test precisely because the structural reasons behind weak days – weekend effects, institutional positioning patterns – apply across index markets, not just one.
How to Implement the Twisted DOW in Your Strategies
Here is a simple process you can follow to apply this day of week trading strategy to any existing breakout system:
- Run your baseline strategy and record the overall average trade.
- Break down performance by day of week. Look at the average trade, win rate, and profit factor for Monday through Friday separately.
- Identify the clearly weak days. Do not look for the “worst” day in a statistical tie. Look for days that stand out as genuinely poor performers – significantly below the average.
- Exclude those days and re-run your backtest. Compare the new average trade to your baseline.
- Validate on at least one other correlated market. If the same exclusion helps on another index, you likely have a real edge improvement.
- Keep it conservative. Exclude one or two days maximum. If you find yourself wanting to exclude three or more days, the strategy itself probably needs work rather than more filtering.
If you are just getting started with building and filtering breakout strategies, our beginner’s guide will give you the foundation you need before applying advanced techniques like the Twisted DOW.
Key Takeaways – The Twisted DOW Strategy
- The classic day of week approach – trading only the best days – is prone to overfitting and instability.
- The Twisted DOW flips this: exclude the worst-performing days instead of selecting the best ones.
- In our real example, excluding Monday and Tuesday improved average trade from $59 to $104 – a 76% improvement.
- Exclusion-based filtering is more robust because negative edges are structurally stickier than positive ones.
- Always validate day-of-week filters across multiple correlated markets to confirm the effect is real.
- Keep exclusions conservative – remove one or two days maximum to maintain sample size and statistical confidence.
Want to learn advanced filtering techniques and build strategies that hold up in live trading? BreakoutOS includes the Best Breakout Filters Finder and Filters Robustness Tester – tools that validate your filters before you risk real money. Explore the platform at breakoutos.com