Flat Base Setup
O'Neil's second-stage setup. After a stock has already made a meaningful advance, it consolidates in a tight, flat range — no more than 15% depth — for at least five weeks. Flat is the key word: there's no rounding or dramatic dip. This shows the stock is under heavy accumulation and sellers can't push it down.
Target before stop: 8% reached +20% before −8% within 40 sessions. Sample: n=146 eligible setups. Average: -0.3% per setup (-0.04R).
Source-bar window: 2024-11-01–2026-10-26. Entry requires an executable breakout fill after the signal; unresolved setups receive the full replay window. Historical and illustrative, not predictive. No brokerage slippage, fees, taxes, or individualized sizing.
How this is measured →Setup Criteria
- › Prior uptrend of at least 20% before the base
- › Base depth: maximum 15% from high to low
- › Base duration: 5+ weeks
- › Very tight weekly closes — almost no range
- › Volume dries up during the base, surges on breakout
Breakout above the flat base high on 40%+ above-average volume.
Just below the bottom of the flat base.
Worked Example
TECH — flagged as a Flat Base on Sep 25, 2026 (score 95). 26 weekly bars with the 10-week SMA.
Entry / stop / target annotations are drawn for Pro members. Unlock →
Historical detection shown for education — not a current recommendation.
What Happened Next
Forward returns after the scanner first flagged a Flat Base (score ≥ 70, gatekeeper passed, one signal per base) — computed from stored daily bars, no lookahead. 100 historical signals.
| After | Median Return | % Positive | Sample |
|---|---|---|---|
| 5 sessions | +0.3% | 52.0% | 100 |
| 10 sessions | -0.3% | 47.5% | 99 |
| 20 sessions | +1.6% | 62.6% | 99 |
| 40 sessions | +0.1% | 50.6% | 87 |
Median best move inside 40 sessions: +7.4% · median worst drawdown: -5.8%. Past scanner behavior does not guarantee future outcomes. Not investment advice.
No Flat Base setups in the latest scan
Market conditions may not be producing this pattern right now — the scanner re-checks every trading day.
