200 moving average and market regime: when to even be in the market

Market Regime is the answer to one question: what kind of market are we operating in right now? The most common and simplest definition uses a single rule: when a broad index — usually SPY, the ETF tracking the S&P 500 — trades above the moving average of the last 200 trading days, the market is in a bullish regime; when it trades below it, the market is in a bearish regime.

This sounds simplistic, and it's intentionally simplistic. The advantage of a crude definition is that you can't argue with it and can't bend it after the fact, and it changes slowly enough that you won't get dragged along by every fluctuation. The interesting question is what you do with the answer.

Why specifically the 200 average

A 200-day moving average compresses about 200 trading days — close to ten calendar months — into a single line, which makes it slow and stable: a two-week correction barely moves it. It's also one of the most widely watched lines in the world — funds, analysts, and retail traders all look at the exact same line, and the multitude of eyes adds behavioral weight to it. More on this family of tools in the guide Moving averages.

There's no magic in the number 200 itself — 150 or 250 would have been equally reasonable. The principle is to choose one slow rule and stick with it, instead of switching rulers every time the result doesn't suit you.

Why filter trades by regime

Most stocks are correlated with the index: when the entire market falls, even attractive setups in strong stocks tend to fail more frequently, because the tide that lifted everyone has turned into a low tide. That's why many swing traders use the regime as a filter: in a bullish regime they operate as usual; in a bearish regime they reduce position sizes, raise the entry bar — or simply sit on the sidelines.

Note what the filter doesn't try to do: it doesn't predict the next decline and doesn't identify a bottom. It only asks whether the environment supports the type of trades you make — like a farmer who doesn't plant in winter. It's a decision about exposure, not a prophecy.

The cost of the filter — because every choice has a cost

A regime filter charges payment in three currencies. First, lag: the 200 average confirms a reversal months after the actual peak or trough, so you'll always miss the beginning of the move. Second, whipsaws: when the index flickers around the line, the filter flips back and forth repeatedly and generates decision noise. Third, breakout days: some of the sharpest up days in history occurred precisely below the 200 average, within bearish markets — those who are out miss these too.

Still, many traders pay this price with open eyes, because what's gained in return — avoiding the most destructive periods — matters more to them than missing the starts. It's a conscious trade-off, not a trick.

How this is implemented in TechAnalyzer's engine

For us, the filter isn't a theoretical recommendation but active code: after backtesting on our track record showed that new setups opened during a bearish regime contributed, on average, a negative result, the engine blocks the opening of new setups when SPY trades below its 200 average. The same measurement also led us to remove short setups entirely — details in the guide on Short selling.

These decisions cost us trades that weren't opened, and some of them would have succeeded — that's the price, and we paid it knowingly, because the data showed that the overall picture improves when you give up trades in a hostile environment.

What this doesn't mean

Three caveats important to keep in mind alongside the filter:

• A bearish regime is not a crash prophecy: A market can cross below the average, chop around for weeks, and return above it. The filter flags an environment, not a price target.
• A bullish regime is not a safety net: Even in a bullish market, individual trades fail all the time. Risk management at the trade level — stop and position sizing — is never rendered unnecessary.
• The line itself is not a wall: A single day's crossing is not an event. Many traders require confirmation — several consecutive closes beyond the line — before they switch regimes in their head.