Patterns › Continuation
Flat Base pattern
A flat base is a continuation pattern in which a stock trading within 30% of its 52-week high pauses in a contained range for at least four weeks, with price near the top of the base before a possible breakout.
Stocks forming it now ↓
What does a flat base look like?
Our scanner checks it as a setup where all of these hold:
- A base 20 to 70 trading days long whose high is 5% to 25% above its low.
- The base doesn't have to move sideways. Price only has to stay inside that range.
- Price within 30% of its 52-week high.
- Price within 5% of the top of the base.
- A prior advance and volume aren't checked.
How reliable is the flat base pattern?
In our most recent backtest (March – September 2026, out-of-sample), 46.2% of the 3,070 highest-scoring flat base setups, out of 82,905 studied, were trading higher two weeks later.
In our analysis of 34,312 flat base trades, low-scoring setups were close to a coin flip, and the high win rates of the top scores did not hold up on newer data.
What makes a flat base fail?
- A weak first-day close, in the bottom fifth of the day's range.
- A big opening gap either way: down more than 5%, or up more than 3%.
- A failed throwback, or no advance at all. Trades that never moved up almost always lost.
- A long base, over 55 trading days.
- A strong, high-confidence bull market, where the score stopped predicting results.
- Declining volume in that kind of market, the reverse of the textbook rule.
From our analysis of past flat base setups.
How are entry, stop and target set?
Every pick comes with an entry zone, price targets and a stop. The targets come from how far past flat base setups actually moved, not from a textbook projection of the pattern's height. The stop scales with the stock's own average daily range, so a volatile stock gets a wider stop than a quiet one.
How is it different from a volatility compression?
Both are bases near a recent high. Our flat base looks at how tall the base is and how close price is to its 52-week high, while our volatility compression usually starts at the 60-day high and checks that daily price swings aren't widening.
Stocks forming a flat base now
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