On-Balance Volume (OBV)

On-balance volume (OBV) is a cumulative indicator that adds volume on up days and subtracts volume on down days. If a stock closes higher than the previous day, the entire day's volume is added to the running OBV total. If it closes lower, the day's volume is subtracted. The resulting line shows whether volume is flowing into or out of a stock over time. The absolute number does not matter — the direction and shape of the OBV line is what counts.

Why It Matters

Volume precedes price. Before a stock breaks out or breaks down, the volume flow often shifts first. OBV captures this shift in a way that raw volume bars cannot. A stock might be trading sideways, but if OBV is rising, money is accumulating quietly — a breakout may be coming. If OBV is falling while price holds steady, distribution is happening and a breakdown could follow.

For options traders, this has direct implications. If you spot OBV diverging from price, you can position early with options and benefit from leverage when the move materializes. OBV confirmation also gives you confidence to hold a position. When both price and OBV are rising together, the trend has real participation behind it.

How It Works

Calculation:

• If today's close > yesterday's close: OBV = Previous OBV + Today's Volume
• If today's close < yesterday's close: OBV = Previous OBV - Today's Volume
• If today's close = yesterday's close: OBV = Previous OBV (unchanged)

Key signals:

• OBV rising with price rising: Confirmed uptrend with volume support. Bullish strategies have higher conviction.
• OBV falling with price falling: Confirmed downtrend with volume support. Bearish strategies are justified.
• OBV rising while price is flat: Accumulation is happening. Smart money may be buying before a breakout. Watch for a long entry.
• OBV falling while price is flat or rising: Distribution is happening. The rally may not be sustainable. Be cautious with bullish trades.
• OBV breakout: When OBV breaks to a new high before price does, it often leads a price breakout. This is one of OBV's most powerful signals.

Limitations: OBV treats every up day and down day equally regardless of the size of the move. A stock that closes one cent higher gets the full day's volume added. This can distort the indicator on days with very small price changes but high volume. OBV also does not account for where within the day's range the stock closed.

Quick Example

A stock trades in a tight range between $48 and $52 for a month. Price looks boring. But OBV has been steadily climbing, making new highs every few days. You interpret this as accumulation and buy a call at the $53 strike with 45 days to expiration. Two weeks later, the stock breaks above $52 on heavy volume and runs to $56. The OBV divergence gave you an early warning that the breakout was coming.