Balance of Power

Momentum

What it measures

Balance of Power measures which side — buyers or sellers — controlled each trading session, by comparing where the close ended up relative to the open against the full high-low range of the bar: (Close − Open) / (High − Low). A short moving average then smooths the day-to-day noise. It's a direct, intuitive read on who "won" each session, rather than an inferred momentum calculation.

How readings are interpreted

Positive BOP means closes have been finishing in the upper part of each bar's range relative to the open — buyers in control. Negative means sellers in control. Because it's normalized by the bar's own range, it's naturally comparable across different volatility conditions and different securities.

Conventional levels

BOP consistently positive: sustained buying pressure
BOP consistently negative: sustained selling pressure
BOP crossing zero: control shifting from one side to the other
BOP diverging from price (e.g. price rising while BOP falls) warns that the rally is happening on weakening buyer conviction

Where it works, and where it does not

Works across most market conditions since it's a direct measure of intrabar behavior rather than a lagging derived calculation, though like any single-bar-based measure it's noisier on more volatile securities and benefits from its smoothing period.

Commonly read alongside

Volume: BOP strength confirmed by rising volume is more meaningful than BOP alone
RSI: BOP divergence alongside RSI divergence strengthens a potential reversal case
Elder Ray: Both come from Alexander Elder's toolkit and address a similar question — combined agreement adds confidence

Known limitations

A single strong or weak bar can swing BOP significantly before smoothing catches up
Doesn't distinguish between a genuine trend and a single volatile news-driven session
Less widely followed than RSI or MACD, so there's less consensus on standard threshold levels

In practice

Use BOP divergence from price as an early warning sign rather than a standalone entry trigger
Conventionally read alongside a volume or trend confirmation rather than in isolation
The zero-line cross is the simplest actionable trigger if you want a single screenable signal
More useful as a secondary confirmation tool than as the primary basis for a trading decision

Plot it yourself. Add this indicator to a chart, change every parameter and watch the line move, then backtest how the rule would have behaved on historical data — free on the S&P 500 ETF, no card.

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This is reference material, not advice. It describes what each indicator measures and how its readings are conventionally interpreted. Nothing here is a recommendation to buy or sell anything, and no indicator predicts future prices. GU Analyser is an analytical tool — no money is ever traded here.