The Bull Flag starts with a sharp rally (the pole), followed by a gentle downward-sloping consolidation channel (the flag). Breakout above the flag's upper trendline continues the uptrend. A widely used continuation pattern.
A pole from 100 to 115 in five days, then eleven days drifting down to 110 (a fitted slope of −0.32 a day). Day 16 closes at 116, above the flag’s high of 115. Measured move: 115 + 15 = 130.
The example data
The turning points the daily closes run through, in straight lines between them; high and low are half a point either side of each bar.
| Day | Close |
|---|---|
| 0 | 100 |
| 5 | 115 |
| 7 | 112 |
| 9 | 114 |
| 11 | 111 |
| 13 | 113 |
| 15 | 110 |
| 16 | 116 |
- A flag that drifts too long, or gives back most of the pole, is no longer a pause but a reversal.
- On real data the pole and flag lengths have to be chosen; the 5 and 11 bars here are fixed to this example.
- The target assumes the second leg equals the first, and it often falls short.
c = df['close'] pole = c.iloc[-12] - c.iloc[-17] # the 5-bar rise flag = c.iloc[-12:-1] # the 11 bars after it slope = np.polyfit(np.arange(len(flag)), flag.values, 1)[0] is_flag = pole / c.iloc[-17] > 0.08 and slope < 0 # sharp rise, then a drift down breakout = c.iloc[-1] > flag.max() target = flag.max() + pole
Assumes import numpy as np, import pandas as pd, and a DataFrame df with columns open, high, low and close for the data above.
- Encyclopedia of Chart Patterns (2nd ed.), T. N. Bulkowski, Wiley, 2005 — success and failure rates from large counts of patterns
- Technical Analysis of Stock Trends, R. D. Edwards & J. Magee, 1948 (later editions revised by W. H. C. Bassetti)
Last reviewed October 2026 · How this site checks its content · Report a mistake
1. What does a bull flag consist of?
Show answer
C. The flag is a pause after a strong move; the pattern is read as continuation if price breaks above it.
2. What volume pattern is traditionally expected?
Show answer
C. Falling volume during the flag is read as a lack of selling pressure — a heuristic, not a rule.
3. How is the classic target set?
Show answer
C. Measured moves assume the second leg repeats the first — a symmetry with little evidence behind it.