Tape speed

What the tape is and what its speed measures

The tape is the sequence of executed trades, one line per print, each with a price, a size and a side (at the bid or at the ask). Tape speed counts how many of those prints arrive per unit of time. A fast tape means many participants are transacting; a slow tape means the market is waiting. Speed says nothing by itself about who is winning: a burst of prints can be buyers lifting offers, sellers hitting bids, or both sides trading against each other at the same price.

Two normalizations exist and they are not interchangeable. Trades per minute needs the real duration of each bar or window; trades per bar is a raw count that depends on the bar type. On a tick bar the count is fixed by construction, so speed has to be read as time per bar instead.

Two ways to count it

• Time-normalized: number of trades in a window divided by the elapsed time of that window, giving trades per minute. It is only defined when the source provides the duration of a closed bar, or when the timeframe is a time interval and the next bar confirms the close.
• Per-bar smoothed: an exponential moving average of the trade count of each bar, in trades per bar. No clock is involved, so it is safe on tick, volume and range bars, but the unit is different.
• Whatever the method, the current bar is incomplete. Its count is partial and a proper implementation leaves it undefined rather than extrapolating.

How to read a change in tape speed

• A sudden acceleration at a level that has been quiet usually means a resting order is being tested; pair it with delta to see which side is aggressive.
• Speed rising while price stalls is the raw material of absorption: many prints, little travel. See the effort versus result entry for the ratio view of the same idea.
• Speed collapsing after a move suggests that the participants who drove it have stopped; it does not by itself say the move will reverse.
• Compare speed with the same session and instrument. The open, the cash close and news releases have their own baseline, and a fast overnight tape may still be a slow day-session tape.

In Senzoukria

Two pane indicators cover the concept. Tape Speed (indicator id speed-of-tape, group Tape & flow) normalizes to trades per minute over a sliding window of N bars (Window, 5 by default) and only uses a bar duration supplied by the data source or implied by an explicit time timeframe whose close is confirmed by the following bar; a tick, volume or range bar with no measured duration gets no value. Tape speed EMA (tape-speed-ema) smooths the per-bar trade count with a standard EMA (period 10 by default) and keeps the unit in trades per bar, with no output during the warm-up. The first one is labelled Tape speed · trades/min in the indicators panel, and both leave a gap during their warm-up.

Both rely on trade counts delivered by the connected feed, so they need per-trade data rather than aggregated bars. Market data is billed by the provider, not by the software.

Common mistakes

• Reading trades per bar on tick bars as if it were a speed: the count is constant by definition.
• Treating a fast tape as bullish or bearish. Speed is activity; direction comes from delta, imbalances and price.
• Comparing a smoothed EMA line with an unsmoothed trades-per-minute line as if they shared a scale.
• Filling the last, unfinished bar with a guessed value. A missing measurement should stay missing.