Volume Oscillator (VO)

Percentage difference between a fast and slow SMA of bar volume. Highlights short-term volume regime changes (spike days vs quiet days) independent of price. A positive reading means short-term volume is running above the longer-term average (rising participation); negative means the opposite.

Quick reference

Item	Value
Family	Volume
Input type	Candle (uses volume)
Output type	f64
Output range	unbounded above and below -100
Default parameters	fast, slow both required (typical 14, 28)
Warmup period	slow
Interpretation	> 0 rising participation; < 0 drying volume

Formula

VO_t = 100 · (SMA(volume, fast)_t - SMA(volume, slow)_t)
       / SMA(volume, slow)_t

A slow average of 0 (only possible if every volume in the slow window was zero) collapses the output to 0 rather than NaN. See crates/wickra-core/src/indicators/volume_oscillator.rs.

Parameters

Name	Type	Default	Constraint	Description
fast	usize	none	> 0, < slow	Fast volume SMA period.
slow	usize	none	> 0, > fast	Slow volume SMA period.

Inputs / Outputs

Indicator<Input = Candle, Output = f64>. Python / Node: standard binding shapes.

Warmup

warmup_period() == slow. First emission lands when the slow SMA seeds.

Edge cases

• Zero-volume slow window. Output 0 (avoids NaN).
• Volume = 0 bar. Contributes zero to both SMAs.
• Reset. Clears both inner SMAs.

Examples

Rust

use wickra::{BatchExt, Candle, Indicator, VolumeOscillator};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let candles: Vec<Candle> = (0..50).map(|i| {
        let v = if i % 5 == 0 { 5000.0 } else { 1000.0 };
        Candle::new(100.0, 101.0, 99.0, 100.5, v, i as i64).unwrap()
    }).collect();
    let mut vo = VolumeOscillator::new(14, 28)?;
    println!("row 30 = {:?}", vo.batch(&candles)[30]);
    Ok(())
}

Python

import numpy as np
import wickra as ta

n = 50
vol = np.where(np.arange(n) % 5 == 0, 5000.0, 1000.0)
vo = ta.VolumeOscillator(14, 28)
# Need candle inputs; bindings expect h/l/c/v

Node

const wickra = require('wickra');
const vo = new wickra.VolumeOscillator(14, 28);
// ...

Streaming

use wickra::{Candle, Indicator, VolumeOscillator};

let mut vo = VolumeOscillator::new(14, 28).unwrap();
let candle_stream: Vec<Candle> = Vec::new(); // your live OHLCV feed
for bar in candle_stream {
    if let Some(v) = vo.update(bar) {
        if v > 20.0 { /* participation rising — confirms moves */ }
        if v < -20.0 { /* volume drying — fade trend signals */ }
    }
}

Interpretation

• Volume regime filter. Use VO as a gate on price signals: trend-following entries on positive VO (volume confirms), mean- reversion on negative VO (low conviction trend).
• Spike detection. VO > +100 typically means recent bars carried 2x the longer-term volume — outlier days.
• Pair with price oscillators. Layer VO over MACD or StochRSI to filter false signals during quiet periods.

Common pitfalls

• Treating absolute level as universal. Magnitude depends on the instrument's typical volume distribution. Calibrate thresholds per instrument.
• Confused with Klinger / KVO. KVO is volume-direction-aware; Volume Oscillator is direction-blind (just uses volume).
• Mismatched periods. fast >= slow is rejected by the constructor.

References

• Standard practitioner indicator; documented in Steven Achelis, Technical Analysis from A to Z (2000).

See also

• Obv — cumulative signed volume.
• Kvo — direction-weighted volume oscillator.
• Vzo — bounded volume-zone alternative.
• Indicators-Overview — full taxonomy.