⚠️ Personal research and trading journal — not investment advice. The author does not provide licensed advisory services.
Paul Tudor Jones, one of the most consistently profitable macro traders of the past four decades, has one simple rule about individual stocks: he will not own a stock that is trading below its 200-day moving average.
The reasoning is clean. A stock below its 200-day MA is in a long-term downtrend. Buying a downtrending stock hoping it will recover is a mean-reversion bet. Mean reversion and momentum don't mix well in the same portfolio. PTJ trades momentum. The 200-day rule is a filter to keep his book consistent with that framework.
When I read this, I tested it.
What the Data Showed
I backtracked through my paper trading entries and my backtest data to separate two groups:
- Group A: Entries where the stock was above its 200-day MA at the time of entry
- Group B: Entries where the stock was below its 200-day MA at the time of entry
The results were directionally consistent with PTJ's rule across all markets I tested:
US data (2020-2025): Group A showed materially higher win rates and average R per trade than Group B. The gap was largest in confirmed-uptrend market conditions — when the market was in a confirmed uptrend (PTJ's preferred environment) and the individual stock was above its 200-day, entries performed significantly better than the same setup with the stock below its 200-day.
Thai data (2015-2025): Similar pattern. Stage 2 (stock above 200-day, 200-day trending up) produced better outcomes than setups that met other criteria but had the stock below the long-term average.
The 200-day rule wasn't adding edge by itself — most of my primary screen (RS≥80, Stage 2 requirement) already implied the stock should be above a rising 200-day. But I identified cases where a stock could pass RS≥80 while still being technically below the 200-day (primarily during sharp but recent recoveries from deep corrections). The PTJ filter eliminates those edge cases.
The Logic Behind the Rule
The 200-day moving average is a long-term trend indicator. A stock consistently above its 200-day has demonstrated sustained buying interest from institutions and longer-term investors over approximately one year. A stock below it has not.
For a momentum strategy, the question isn't just "is this stock going up today?" but "is there a reasonable expectation that the uptrend will persist long enough to matter?" Stocks below their 200-day tend to mean-revert more, hold rallies less long, and fail breakouts more often.
There's an additional structural reason: institutional buyers often have 200-day rules of their own. Many fund mandates and risk management systems flag stocks below the 200-day as technically weak. When you buy a stock above its 200-day, you have institutional rebalancing as a potential tailwind. Below it, you're working against those flows.
How It's Implemented
In my live scanners (scan_di_live*.py for both Thai and US), the 200-day veto is wired as a hard gate. A stock that passes every other filter — RS≥80, contracting base, volume dry-up, Stage 2 — is still excluded if it's below its 200-day moving average.
There's one exception: I don't apply the veto mechanically on stocks that are in an early Stage 2 rebound from a deep correction (where the 200-day is still declining but the stock has made a strong first thrust upward and established a higher low). In those cases, I rely on the RS score and chart read more than the MA absolute level. But that's a judgment call applied sparingly, not a systematic override.
The veto triggers most commonly on: - Stocks that had strong RS momentum for 1-3 months but were recovering from a deep prior base below the 200-day - Stocks in turnaround situations (classic value trap territory) - ETFs or indices where MA levels are less predictive at the individual stock level
The Broader Principle
PTJ has said that the 200-day rule prevents him from "catching falling knives." It's a momentum purity principle: if you're a momentum trader, don't hold positions that violate the most fundamental definition of a sustained uptrend.
The rule isn't about precision. The 200-day MA isn't magic. But as a filter, it eliminates a class of setups where the risk/reward is systematically worse than what a momentum framework is designed for. It keeps the portfolio internally consistent.
I've found in practice that the most reliable setups aren't the ones where a stock is recovering toward the 200-day — they're the ones where the stock crossed the 200-day months ago, built a base well above it, and is now breaking out from that base. The 200-day is almost invisible by that point. Which is exactly when you want to be buying.
Track. Study. Wait. Strike.
Personal research and trading journal — not investment advice. The author does not provide licensed advisory services. — MOEasymmetry
Draft 2026-06-12. Source: PTJ 200-day rule traced to public interviews and letters (not primary document). Implementation: scan_di_live.py and scan_di_live_us.py — hard gate. Backtest validation: directional finding on US 2020-2025 and Thai 2015-2025 data; groups defined by above/below 200-day MA at entry. Precise statistics available in backtest data but not cited here — the principle is the focus. Exception noted: Stage 2 rebound judgment call, applied sparingly.