Indicators
Volume, VWAP, and order flow: know your data source
Understand traded volume, tick volume, VWAP, OBV, and order-book evidence, including the limits of fragmented crypto and OTC market data.
By atradeaday · Published
Volume can add information about participation, but only if you understand what the number measures. Exchange-traded volume, tick counts, and aggregated vendor estimates are different datasets. A missing value should not silently become evidence of weak participation.
Start with provenance
Record the venue, unit, interval, and whether the volume includes the entire market or only one trading venue. Crypto activity is fragmented across venues. OTC instruments may expose tick activity rather than consolidated traded size. Comparisons can be misleading when the measurement changes between instruments.
A breakout accompanied by more reported activity is an observation worth testing. It does not establish the identity or intention of the participants. Avoid assigning institutional motives to a candle without evidence.
VWAP and the anchor
Volume-weighted average price is the sum of price times volume divided by total volume for the selected window. A bar-based approximation often uses a representative candle price; it can differ from transaction-level VWAP. Session VWAP resets at a session boundary, while an anchored VWAP begins at a chosen event or timestamp.
A hypothetical pair of trades, 10 units at 100 and 30 units at 102, has a VWAP of 101.5. That is a historical weighted average. Trading above it does not guarantee a profitable long, and changing the anchor changes the reference.
For a market open around the clock, specify the timezone and reset time rather than assuming all platforms use the same session.
OBV and order-book evidence
On-balance volume accumulates reported volume positively or negatively according to the direction of the closing-price change. It simplifies a complex sequence into one series and can hide intrabar activity. Use it as a defined feature, not a direct view of buying or selling intent.
An order book shows displayed resting interest. Orders can be cancelled, hidden liquidity may exist, and a screenshot ages quickly. Historical candle data alone cannot reproduce the queue dynamics required to test a detailed order-flow strategy.
A practical validation sequence
Check for missing intervals and abnormal units. Compare activity with a consistent reference window or session. Then measure whether a volume condition improves a baseline setup after costs. Exclude unavailable-volume cases or label them explicitly rather than inventing confirmation.
See Fidelity's indicator catalog for volume-based indicators. Continue with execution and slippage for why a visible price and an achievable fill can differ.