Impulse Waves (12345): Structure and Rules

The impulse wave is the directional engine of Elliott Wave Theory. Whenever a market trends strongly, an impulse is unfolding. Understanding its anatomy is the foundation of every wave count.

What is an impulse wave?

An impulse is a five-wave sequence labeled 1-2-3-4-5 that moves in the direction of the larger trend of one higher degree. It contains:

• Wave 1: the initial move, often dismissed by the crowd as "just a bounce"
• Wave 2: a partial retracement that shakes out early buyers
• Wave 3: the powerful middle wave, where the trend becomes obvious and volume surges
• Wave 4: a sideways or shallow pullback as the trend consolidates
• Wave 5: the final push, often momentum-driven and emotionally charged

The three unbreakable rules

For a five-wave sequence to be a valid impulse, three rules must hold:

1. Wave 2 never retraces more than 100% of wave 1. If it does, the count is wrong — wave 1 is invalidated.
2. Wave 3 is never the shortest of the three motive waves (1, 3, 5). It can be the longest, but never the shortest.
3. Wave 4 never enters the price territory of wave 1. Overlap means you're looking at a corrective pattern, not an impulse.

Break any rule and the entire count must be relabeled.

Internal structure

Each motive wave (1, 3, 5) of a larger impulse is itself a five-wave impulse of smaller degree. Each corrective wave (2, 4) is a three-wave (ABC) correction. This nested structure is what makes Elliott Wave fractal.

Wave 3: the trader's favorite

Wave 3 is where most money is made. It is usually the longest, has the steepest slope, and confirms the trend direction beyond doubt. Traders who wait for wave 2 to end and enter on the start of wave 3 — confirmed by a break of the wave 1 high — capture the cleanest leg of the move.

Wave 5 characteristics

Wave 5 is often shorter than wave 3 and may show divergence on momentum oscillators like RSI or MACD. In commodity markets, fifth waves can "extend" dramatically, but in equities they often lag. When wave 5 fails to exceed wave 3's extreme, it's called a truncation or failed fifth — a warning of trend exhaustion.

Practical identification checklist

• Confirm the larger-degree trend direction
• Identify five clear, non-overlapping legs
• Verify wave 2 retracement (commonly 50%–61.8%)
• Check that wave 3 shows strongest momentum
• Ensure wave 4 stays above wave 1's high (in an uptrend)

A valid impulse gives you the trend's skeleton. Master impulse structure before tackling the far messier world of corrective waves.