How to Double Your Profit on E-mini S&P 500 and NASDAQ With One Simple Trick
What if I told you there is a simple formula that can dramatically increase your profit on E-mini S&P 500 and NASDAQ – and you can implement it in literally one minute? It sounds too good to be true, but I have the evidence to back it up. This is one of my oldest trading tricks, something I have been using for over a decade, and it just keeps working like a charm.
The technique is dead simple: only trade long after down days. That is it. If Monday was a down day and it is now Tuesday, the odds of having a much higher quality long trade on Tuesday are significantly better. But the real power of this approach only becomes visible when you analyze it the right way – and that is exactly what I am going to show you.
Why This Approach Works on Index Futures
E-mini S&P 500 and E-mini NASDAQ have a well-documented long bias. Over time, these indexes trend upward. But not every day offers the same quality of opportunity. After a down day, there is a natural tendency for the market to bounce – buyers step in, short positions get covered, and the upward bias reasserts itself.
What makes this more than just a theory is the data. I tested this across decades of market history, and the results are consistent and robust. This is not a temporary anomaly – it is a structural feature of how index markets behave. And the best part is there are no optimizable inputs, which means virtually zero risk of overfitting when you add this to your existing breakout trading strategy.
The Evidence on E-mini S&P 500
Here is where it gets interesting. I did not just test this the traditional way by looking at open-to-close returns after down days. Instead, I analyzed every hourly bar from 2007 to 2023 – nearly 79,000 bars – to see how the quality of each individual bar changes after a down day.
The results on E-mini S&P 500:
- Average hourly bar quality increased by 141% when trading long after a down day
- Normal average bar: $2.30 per hour. After down day: $5.56 per hour
- Hold a position for 20 hours normally: about $46 average profit. After a down day: over $110 average profit
- Trading only after down days captured nearly the same total profit ($132K vs $181K) while being in the market only 30% of the time
Read that last point again. You make roughly 73% of the total profit while only being exposed to the market 30% of the time. That is a massive improvement in capital efficiency and risk-adjusted returns. The number of bars traded dropped by 70%, but the profit barely declined.
This is why looking at hourly bar quality matters more than simple open-to-close analysis. It shows you that after a down day, virtually any reasonable long entry – even something as simple as a basic breakout of the first 30 minutes – has significantly better odds of success.
NASDAQ Results Are Even More Impressive
The same technique applied to E-mini NASDAQ shows similarly powerful results. NASDAQ was a quieter, lower-volatility market before roughly 2015-2017, so the equity curve looks flat during that earlier period. But once volatility picked up, the after-down-day edge on NASDAQ absolutely exploded.
If you stripped out the low-volatility era and measured only the high-volatility period, you would see hundreds of percent improvement compared to the baseline. The average hourly bar quality on NASDAQ after a down day is roughly double the quality of a normal bar – a substantial edge by any measure.
This technique also works on other indexes, though the best results come from S&P 500 and NASDAQ. You will see weaker results on E-mini S&P 400 (EMD) or E-mini Russell 2000 (RTY), which makes sense because those indexes have less of an inherent long bias compared to the major indexes.
The Formula – Simple Enough for Any Platform
In TradeStation, the code is straightforward:
If Close(D,1) < Open(D,1)
That translates to: if yesterday’s daily close is lower than yesterday’s daily open, then it was a down day, and we activate our long filter. That is the entire formula. It works on both full sessions (midnight to midnight) and regular trading hours (8:30 AM to 3:15 PM). My research shows the full session tends to work slightly better, but the difference is not huge – both are effective.
If you use a different trading platform, the logic is the same. You are simply checking whether the previous day closed below its open. Any platform that supports daily reference data can implement this in seconds.
Three Ways to Implement This Today
Here is how to put this to work immediately, from simplest to most involved.
1. Add It as a Filter to Existing Strategies
Take any long index strategy you already trade on E-mini S&P or NASDAQ. Add the down-day condition as a filter. There is no optimization involved – it is a single binary condition – so you are not adding curve-fitting risk. Many traders see an instant and dramatic improvement in their equity curve.
2. Use It as a Master Filter for Strategy Development
When building new breakout strategies, start with this as a preliminary filter. Tell your development process: only look for long entries on days after a down move. Then build your entries, exits, and other conditions on top of this foundation. You are starting with a built-in edge before you even begin optimizing.
3. Double Your Position Size After Down Days (My Favorite)
This is my preferred approach and the one I use most in my own trading. Keep your existing strategy running as-is on all days. But when yesterday was a down day, double your position size. Your probability of profit is significantly higher, so you are allocating more capital when the odds are most in your favor.
This method preserves your full sample size (you do not lose any trades), maintains your strategy’s baseline performance, and adds meaningful extra profit on the highest-probability days. It is the best of both worlds.
Why Bar-by-Bar Analysis Reveals More Than Open-to-Close
A standard backtest might show you that long trades after down days are profitable. But the hourly bar analysis reveals something much deeper – the quality of the move inside the day itself is fundamentally better.
It is not just that the day closes higher. Every hour within that day carries more upward momentum, more consistency, more reliability. This is why even simple entry methods work well after down days. The entire session is saturated with higher-quality long opportunity. Whether you enter on a morning breakout, a pullback to a moving average, or any other method, the underlying conditions are working in your favor.
This kind of insight is impossible to get from traditional open-to-close analysis, and it is why I recommend every serious algorithmic trader to start looking at markets from this intraday perspective.
A Timeless Edge You Can Use Right Now
I have been using this technique for over a decade. It is one of the most robust, evergreen edges I have ever found in index trading. There are no complicated indicators, no multi-parameter optimization, no curve-fitting risk. Just one simple observation backed by nearly two decades of data: long trades after down days on E-mini S&P 500 and NASDAQ produce dramatically higher quality results.
Whether you apply it as a filter, a position sizing rule, or a foundation for new strategy development, this single insight can meaningfully improve your trading results – and it takes about one minute to implement.
The only question is whether you are the kind of trader who believes things can be simple and effective, or the kind who insists there must be a catch. Both groups are right – your mindset determines your outcome.
Want more evidence-based techniques to improve your index trading? BreakoutOS includes 20+ professional tools for building, validating, and managing breakout strategies – including Market Mapper and Breakout Trendiness Analysis. Explore the platform at breakoutos.com