Mean Reversion vs. Momentum: Two Strategy Families Every Trader Should Know
Almost every quantitative strategy ever written is a flavor of one of two ideas: things that have moved too far come back, or things that have started moving keep going. Pick the wrong family for the wrong market and you will be confused for months.
Mean Reversion: "It Always Comes Back"
Mean reversion bets that prices oscillate around some equilibrium. A move too far in either direction is an opportunity to fade. RSI under 30, price two standard deviations below a moving average, oversold bounces — these are all the same idea in different clothes.
Mean reversion has high win rates and small wins. It works beautifully in range-bound, low-volatility markets and gets steamrolled by trends. The classic mean-reversion failure mode is shorting strength in a bull market or buying weakness in a crash.
Momentum: "The Trend Is Your Friend"
Momentum is the opposite bet: things that have started moving will keep moving. Buy breakouts, ride trends, exit when momentum fades. Moving average crossovers, channel breakouts, and 12-month returns rankings are all momentum.
Momentum has lower win rates and larger wins. It pays for itself with a few outsized trades each year while losing small amounts on many false starts. The classic momentum failure mode is the choppy market that issues breakout signals every week and never follows through on any of them.
How to Tell Which Regime You Are In
There is no perfect tell, but rough heuristics help. Volatility expansion with directional persistence usually favors momentum. Compressed volatility with frequent reversals favors mean reversion.
The percentage of stocks above their 200-day moving average is a useful broad-market gauge. When it climbs through 60%, momentum tends to work. When it oscillates between 40% and 50%, mean reversion wins more often.
Mixing Both
Many serious traders run one of each. The two families have low correlation in returns — when one is struggling, the other is often fine. The combined equity curve is much smoother than either alone.
This is the same principle as diversification, applied to strategy families instead of assets. You do not have to pick the right regime in advance. You let each strategy take the trades that suit its style.
A Reading Strategy
If you are new and want to start with one family, start with mean reversion on liquid large-caps or major crypto. Win rates are higher, which keeps a beginner emotionally engaged through the inevitable losing streaks. Once a mean-reversion strategy is working, add a momentum overlay. The combination teaches more than either alone.