Arrival Price: the price when an order arrives

In plain terms — It is a snapshot of the market at the start of execution. It compares what was available at that moment with the price obtained later.

Arrival Price is an execution benchmark anchored to a defined instant, such as when an order reaches a desk, broker, or automated system. It is not necessarily the last trade. A method may use the midpoint, bid, ask, or another independent price consistent with the side, instrument, and applicable rules.

“Arrival” alone does not identify the clock. Decision time, release time, and time of order receipt may differ. Moving the timestamp changes the comparison and can remove a real part of the delay from the measurement.

The benchmark is an inseparable pair: a stated instant and a price rule. Select a stage to follow its role.

What it measures

For a buy, the elementary price cost is average execution price minus Arrival Price; for a sell, the sign is reversed. An adverse value does not prove an error: the market may move, the order may be large, or a limit may prevent fills.

The benchmark answers a narrow question: how did price change between the selected instant and execution? Fees, unexecuted quantity, and opportunity cost require additional measures.

Timestamp and reference price

An audit retains the order identifier, side, quantity, time zone and precision, quote source, and price rule. In the European PRIIPs framework, Annex VI uses the mid-market at transmission in several cases and defines alternatives when that price is unavailable. US Rule 605 ties many statistics to order receipt and the relevant NBBO quote.

Those definitions have specific scopes. Futures, FX, crypto, and OTC instruments may require different venues and price mechanisms. Applying a nonexistent NBBO or treating one dealer quote as the whole market creates false precision.

A compact example

A buy order for 10,000 units arrives with a midpoint of 50.00. Fills are 4,000 at 50.03 and 6,000 at 50.05, giving a quantity-weighted average of 50.042. The difference is 0.042 per unit, about 8.4 basis points versus 50.00, before fees and any unexecuted quantity.

Using the ask at 50.02 would answer a different question. A report should therefore expose side, timestamp, and benchmark construction, not just the final number.

Do not confuse the measures

VWAP summarizes prices and volumes over an interval; Arrival Price fixes one instant. Slippage is broader and remains ambiguous until its benchmark is named. Implementation Shortfall begins with the whole investment decision and includes unexecuted quantity.

A favorable Arrival Price result can coexist with high fees or a large residual. An adverse result may reflect a market move not caused by the order.

Advanced level: comparability and attribution

Comparable samples should be segmented by instrument, side, size versus volume, time, urgency, and volatility. Unsynchronized timestamps can attach the wrong quote in fast markets. Conditional orders may require the time they first become executable rather than initial submission.

Arrival Price is observable; the market price that would have prevailed without the order is not. The gap combines market movement, spread, venue selection, impact, and queue randomness. Separating them requires more data and a counterfactual model.

Practical limits

Locked or crossed quotes, delayed feeds, fragmented markets, and OTC instruments weaken the reference. A sound policy defines exceptions before analysis and does not select the most favorable timestamp after seeing the fills.