On-Balance Volume: The Volume Indicator That Leads Price
Price tells you what happened. Volume tells you how convinced people were. OBV is a way to track that conviction over time — and sometimes, OBV starts moving in a new direction days before price does. That's the edge.
OBV leads price — when buying volume is consistently outpacing selling volume even before price moves, institutional accumulation is likely underway. The most actionable OBV signal is divergence: price making a new low while OBV holds higher means sellers aren't finding new supply at lower prices, which often precedes a reversal. APEX uses OBV alongside price trend and MACD to identify whether volume is confirming or contradicting the current price direction.
What Is On-Balance Volume?
OBV is a running total of volume. On days when the stock closes higher than the previous day, that day's full volume is added. On days when it closes lower, the volume is subtracted. The result is a line that rises when buying volume dominates and falls when selling volume dominates.
The actual OBV number means nothing in isolation — it's not a price or a percentage. What matters is the trend and direction of the OBV line relative to price. Are they moving together (confirmation) or apart (divergence)?
Why OBV Can Lead Price
Large institutional orders don't happen all at once — they're worked over days or weeks to avoid moving the market. But volume shows up in OBV even when price barely moves. If a stock's price has been flat for two weeks but OBV is quietly rising every day, that means somebody is accumulating shares steadily. The price reaction comes later, when the buying is complete.
This is why OBV divergences are worth watching. They suggest the smart money is already positioned in a direction that retail hasn't priced in yet.
The Limitation
OBV assigns the full day's volume to the up or down bucket based on the close — which is a crude approximation. A stock that opens at $100, trades as high as $110, but closes at $101 (up $1) would add 100% of that day's volume as "buying" even though most of the intraday action was volatile. More sophisticated volume indicators like VWAP or Chaikin Money Flow address this. OBV is a useful first-pass tool, not the final word.