unfairly assigning clients the worst rate available in relation to 'transaction window' trading
Some client order may be executed over time with client expecting 'at best' price or price linked to a benchmark such as time weighted price or volume weighted price. Inappropriate order fill rates takes place when traders pass worse rate to a client than actually achieved during the order execution.
Effective implementation of surveillance alerts for nappropriate order fill rates requires capturing the following trade data:
trade and position
client order details including specific instructions (e.g. at best, TWAP)
market prices and volumes
Effective surveillance alerts should attempt to re-calculate the expected fill rate based on market data and compare it against the client fill.