Reference point explained

Arrival price is the market price recorded at the moment a trader releases an order or starts an execution schedule. It anchors subsequent measurement of slippage or implementation shortfall by representing the state of the market at the start of action.

Because it fixes the starting line, changes afterward can be attributed to either market impact from the order or to independent market movement, depending on analysis.

Setting the timestamp

Defining the exact timestamp is essential. Some desks use the first quote after order creation; others use the mid-price or last trade at submission time. For multi-venue assets, the reference may be a consolidated mid or an index-based fair value to avoid venue bias.

Consistency across trades is more important than the specific variant chosen. If the timestamp slides, the benchmark and all dependent metrics will drift in ways that mask true performance.

Where it guides execution

Arrival price is widely used for schedule selection and post-trade evaluation. Strategies such as TWAP or adaptive participation track how far execution strays from arrival as they balance speed and impact.

Brokers and algos are compared by average or median slippage from arrival, segmented by notional size and volatility regime. This enables fairer comparisons across days and venues.

Limitations under volatility

In fast markets, the price can move meaningfully between order decision and first executable quote. Latency asymmetry and stale quotes increase the gap. In such cases, using a consolidated or index-derived reference can stabilize results but may hide microstructure nuances.

Analysts should document how they handle crossed markets, halts, or missing quotes at the start. Clear fallbacks keep the benchmark reproducible.

Things to Remember

• Lock the start: Define and fix the timestamp and price source for the arrival benchmark.
• Consolidate smartly: Use a fair composite when venues diverge to avoid selection bias.
• Segment results: Compare slippage to arrival by size and volatility to get actionable signals.
• Handle edge cases: Crossed quotes and gaps need explicit rules to keep metrics comparable.