OBV in NinjaTrader — NinjaScript (C#) Source

OBV is about the simplest NinjaScript indicator you can write — a running total that reads its own previous value. See the explainer for the rule.

What you’ll need

• NinjaTrader 8
• New → NinjaScript Editor → Indicators → New Indicator, name it AlgoGenOBV

The source

#region Using declarations
using System;
using System.Windows.Media;
using NinjaTrader.NinjaScript;
using NinjaTrader.NinjaScript.Indicators;
#endregion

namespace NinjaTrader.NinjaScript.Indicators
{
    public class AlgoGenOBV : Indicator
    {
        protected override void OnStateChange()
        {
            if (State == State.SetDefaults)
            {
                Name        = "AlgoGen OBV";
                Description = "On-Balance Volume (Granville)";
                IsOverlay   = false;

                AddPlot(new Stroke(Brushes.MediumSeaGreen, 2), PlotStyle.Line, "OBV");
            }
        }

        protected override void OnBarUpdate()
        {
            if (CurrentBar == 0)
            {
                Value[0] = 0;
                return;
            }

            double vol = Volume[0];
            if (Close[0] > Close[1])
                Value[0] = Value[1] + vol;
            else if (Close[0] < Close[1])
                Value[0] = Value[1] - vol;
            else
                Value[0] = Value[1];
        }
    }
}

Compile & apply

1. Press F5 to compile.
2. Add AlgoGen OBV to a chart; it draws in its own panel, matching the output chart. Add a moving average of it (or the built-in SMA(OBV(), 20)) for a signal line.

Gotchas

• Value[1] is the running total. Reading your own prior plotted value is what makes the accumulation work; no separate field needed.
• Volume type. On instruments/data series without real volume, Volume[0] may be tick counts. OBV only means something where volume is meaningful.
• Bar-0 seed. Start at 0 on the first bar; everything after builds on it. The absolute level is arbitrary — read the line’s direction, not its value.
• Add a signal line. In a strategy, compare OBV to a smoothed version of itself for tradeable crossovers rather than acting on the raw total:

// In a strategy's OnBarUpdate, using the built-in OBV() and SMA():
if (CrossAbove(OBV(), SMA(OBV(), 20), 1))
    EnterLong();
else if (CrossBelow(OBV(), SMA(OBV(), 20), 1))
    EnterShort();

• Volume type. On Renko/range bars or synthetic series, Volume[0] semantics vary — confirm you’re feeding OBV real traded volume before reading anything into divergences.

That’s the five-language set: Python, MQL5, Pine Script, EasyLanguage, and this one. Now check whether OBV confirms your entries in AlgoGen.

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This post is educational, not financial advice. Indicators describe the past; they don’t predict the future. Backtest anything before you risk real money on it.