GLOSSARY // Orders & Execution
Fill
A fill is the execution of an order: the moment shares actually change hands, stamped with a price, a size, and a time. Until an order is filled it is an intention; the fill is the trade.
Fill quality is measurable. Compare your execution price to the quote at the moment you submitted: filling a buy below the displayed ask is price improvement, filling above it is slippage. Larger orders often come back as several partial executions at different prices, and the confirmation shows the weighted average.
A 1,000-share market buy on a stock quoted $52.08 x $52.10 comes back in three prints: 300 at $52.10, 500 at $52.11, and 200 at $52.13, an average fill of $52.111. Against the $52.10 ask at submission, the order slipped $11 in total.
Related terms
Educational only — not financial advice. Definitions simplified for clarity; markets are messier than definitions.