A running total that adds the period's volume when price closes up and subtracts it when price closes down.
Joseph Granville's indicator is deliberately crude: the entire bar's volume is assigned to one side based only on whether the close was higher or lower than the previous one. A bar that rose one tick counts exactly the same as one that rose five percent.
It is used mainly for divergence. If price grinds to new highs while OBV fails to follow, the argument is that the advance is not being supported by participation.
The crudeness is the honest criticism. Every trade has a buyer and a seller, so attributing volume to one side from the close alone is an assumption, not a measurement. Modern cumulative-delta does the same job with actual aggressor data and makes OBV look like what it is: a 1960s approximation.
Original diagrams for the ideas on this page. Illustrative, not real market data.
Delta across the range of prices. Delta says how much a call's price moves for a one-point move in the stock. Far below the strike it is near 0 and the option barely reacts; at the strike it is about 0.50; far above it approaches 1 and tracks the stock.Divergence between price and RSI. RSI measures how one-sided recent price moves have been on a 0–100 scale. Here price sets a higher peak while RSI sets a lower one, so the second push carried less momentum than the first.
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