Rounding Tops

Core idea

A rounding top is a convex price arch — price rises gently, peaks broadly, and curves back down to roughly the same starting level. The two endpoints (rims) sit at nearly the same price; that even-rim feature is what distinguishes a rounding top from an inverted scallop (where the rims sit at different prices) and from a complex head-and-shoulders top (which has multiple distinct peaks rather than a single dome).

The pattern is named for the shape, not the outcome. A rounding top can break out upward or downward. In bull markets, it breaks upward 58% of the time and posts a strong 55% average rise — ranking second among 20 bull-market upward-breakout patterns. The same shape in bear markets, however, ranks 19th of 20 with only a 23% gain. This is one of the largest performance spreads in Bulkowski's catalogue across the bull/bear divide.

Bulkowski's framing: When is a top not a top? When it is a rounding top and price breaks out upward 58% of the time in bull markets. The shape suggests distribution, but the data says otherwise — most rounding tops resolve in the trend direction, not against it.

Why it matters

The rounding top is the most context-sensitive pattern in the book. The same arch shape that signals exhaustion in a bear market signals consolidation in a bull market. A trader who reads the pattern in isolation will get whipsawed; a trader who pairs the pattern with the prevailing market trend (and the breakout direction) has one of the highest-performing setups in the catalogue.

Why the volume signature is unreliable

Rounding tops often show U-shaped volume — high at the rims, low in the middle. But the volume trend across many examples is close to random, and Bulkowski explicitly warns against using volume as a primary disqualifier. The shape carries the signal; volume only adds (weak) confirmation.

The measure rule rarely fires

Because rounding tops are often tall — months of dome formation across substantial price travel — the full-height measure rule (pattern height projected from breakout) hits only 12–58% of the time depending on direction and market condition. Use a fraction of the height (50% or 60%) for a more realistic target, or use prior structural levels (the dome top, prior support) as the trade plan instead.

Key takeaways

Mental model

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Practical application

Example

A large-cap consumer staple has rallied from $52 to $74 over the prior year. Over the next four months, the stock arches gently to $80, holds there for three weeks, then curves back down to $76 — a textbook dome with the start and end rims at $74 and $76 (within 3%). Volume across the pattern is U-shaped, lower in the middle than at the rims. The broader market remains in a bullish trend.

A trader recognises the shape and waits. Two possible setups:

Upward continuation (preferred in this regime): A close above the $80 dome top is the long trigger. The trader sets a buy-stop at $80.50. Pattern height = $80 - $74 = $6. Full measure rule target = $80.50 + $6 = $86.50; realistic 60% target = $80.50 + $3.60 = $84.10. Stop placed at $75.20 (below the lower rim).

Downward reversal (countertrend, smaller size): A close below $74 would trigger a short. Risk-reward is symmetric, but the bull-market context means this trade is sized at half the position.

Six weeks later, the stock closes at $81.20 on volume well above the dome's average. Long fills at $80.50; risk = $5.30 per share. Eight days after entry, the stock retraces to $80.10 — a textbook throwback to the breakout level — and bounces. The trader holds.

Over the next ten months, the stock advances in choppy stages to a peak at $96.40 — a 20% gain from entry, below the 55% median but well above the realistic 60% target. The trader scales out half at $84.10 (the 60% measure-rule target), trails the rest with a 20-week-low stop, and exits the runner at $93.50 when the trend rolls over. Blended exit: ~$88.80, a $8.30 gain on $5.30 risk — about 1.6-to-1.

The lesson: the rounding top's headline 55% average is distorted by a handful of multi-year monsters. Realistic targets and structural exits capture the middle of the distribution, which is what most trades resemble.

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