OBV Fully Dissected: Tracking Big-Money Accumulation in Numbers
Price can deceive, but volume can't. In 1963 Joseph Granville introduced OBV (On-Balance Volume) in Granville's New Key to Stock Market Profits. Here we take it apart: the core formula, signal-line (EMA) design, real accumulation and divergence cases, the limits of frequent signals, and the data traps even experienced traders miss.
1. Definition and formula: how cumulative volume creates direction
- OBV(t) = OBV(t−1) + Volume(t) · close higher than the previous day
- OBV(t) = OBV(t−1) − Volume(t) · close lower than the previous day
- OBV(t) = OBV(t−1) + 0 · close unchanged
Why change and direction, not the absolute value: OBV is a running total from the first day of data. The absolute value depends entirely on that start date, so all that matters is the change (delta) over a period and whether its highs and lows are rising or falling.
2. Calculate it: BTC, October 12–16, 2020
Right after each daily close, compare today's close with yesterday's to judge up (+), down (−) or unchanged (0), and add or subtract the whole day's volume to the previous OBV with that sign. Even in 5 days, tens of thousands of BTC are added and removed, shaping the OBV curve. (We start from 0 on October 11.)
| Date | Close ($) | vs prior day | Volume (BTC) | OBV |
|---|---|---|---|---|
| 10-12 | 11,528.25 | ↑ add | 52,825 | +52,825 |
| 10-13 | 11,420.56 | ↓ subtract | 42,205 | +10,620 |
| 10-14 | 11,417.89 | ↓ subtract | 41,415 | -30,795 |
| 10-15 | 11,505.12 | ↑ add | 48,761 | +17,966 |
| 10-16 | 11,319.32 | ↓ subtract | 48,798 | -30,832 |
Data: Binance BTCUSDT daily candles (UTC).
3. Signal line: the 20-day exponential moving average (EMA) of OBV
The OBV line alone can't tell a sustained inflow from a passing swing, so a 20-day EMA, which weights recent values more, serves as the signal line. α = 2/(20+1) ≈ 0.0952, EMA(t) = α×OBV(t) + (1−α)×EMA(t−1): about 9.52% of today's OBV plus about 90.48% of yesterday's EMA, seeded with the simple average of the first 20 OBV values. On October 18, 2020, ETH's OBV of 14,835,916 was above its EMA of 14,332,673, so it reads as 'above average (net inflow)'.
4. Signal ① Sideways price + rising OBV: quiet accumulation
When price stands still while OBV climbs steeply on its own, it is read as a classic accumulation pattern: big money absorbing supply without pushing the price. ETH moved −0.9% from $381 on September 3, 2020 to $378 on October 18, yet OBV rose by +7.96M ETH over the same period. 45 days later the price was $597 (+57.9%).
5. Signal ② New price high + falling OBV: bearish divergence
When price breaks above its prior high but OBV makes a lower high, it is called bearish divergence. It is read as a distribution phase in which the real buying behind the rally is fading. BTC rose +6.2% from $63,575 on April 13, 2021 to $67,526 on November 8, yet OBV fell by −0.93M BTC over the same period. Over the next 90 days the price dropped to $42,381 (−37.2%).
6. Signals flip too often: the whipsaw
Apply the simple crossover rule (buy when OBV crosses above its 20-day EMA, sell when it crosses below) to BTC daily data from 2018 to 2026, and the state flips 510 times: about 58 times a year, roughly once every 6 days. Even with the trend condition 'close above the 50-day moving average', it flips 344 times, about 39 a year, more than 3 times a month. That is why a changed signal is easy to miss unless you check every day.
7. Data traps: 4 reasons not to trust OBV blindly
- Failed accumulation: from Aug 21 to Oct 5, 2025, ETH's OBV rose +2.71M ETH and looked like accumulation, yet the price fell −33.0% over the next 45 days. Without an exit rule, that can mean a large loss.
- Exchange volume gaps: in 2021 BTC's average daily volume was 69,924 BTC on Binance and 4,940 BTC on Bitstamp, about 14× apart. Which exchange's chart you use changes the OBV path and its signals.
- Outlier volume: OBV adds or subtracts the whole day's volume regardless of the size of the move. On 2018-11-20, BTC's daily volume was 19.0% of the previous 30 days combined. One such day can shake the whole OBV trend.
- Daily close time: in a 24-hour market, the close (UTC 00:00, KST 09:00, etc.) changes the close and the volume window, and can turn an up day into a down day, flipping the sign itself.
8. Daily routine: 7 steps if you do it by hand
- Confirm the daily close at UTC 00:00
- Compare today's close with yesterday's: up, down or unchanged
- Add or subtract today's volume by that sign to update OBV(t)
- Update the signal line: EMA(t) = α×OBV(t) + (1−α)×EMA(t−1)
- Update the 50-day moving average from the last 50 closes
- Check both: ① OBV above EMA20? ② close above the 50-day line?
- If the state changed from yesterday, log it and act right away
Crypto never takes weekends or holidays off. All of this has to be repeated 365 times a year, without missing a single day.
Will you run this every single day?
Miss checking for just one busy day and you can walk right past a change in the flow. Volume Tide (daily crypto charts only) handles all of this on its own once it's on your chart, and simply shows a clear ▲ RIDE or ▼ OUT. Leave the headache to Volume Tide and just glance at the mark on your chart.
See it on Volume Tide →This is educational material to help with chart analysis. It does not guarantee profits, and investing carries a risk of loss. The percentage moves and flip counts in the cases are calculated from past data and do not guarantee future returns.
Data: Binance BTCUSDT and ETHUSDT, Bitstamp BTCUSD daily closes and volume (UTC); OBV accumulated from 2017-08-17; EMA20 seeded with the first 20-day simple average. OBV concept: Joseph E. Granville, Granville's New Key to Stock Market Profits (1963).