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Price Improvement
Price improvement occurs when an order executes at a better price than the relevant quoted price or the price the trader might otherwise have accepted.
Why it matters to you
Suppose: Bid = $4.80 Ask = $5.20 You want to buy. Rather than immediately paying $5.20, you place a limit at: $5.00 and get filled. You have obtained a better purchase price than the displayed ask at the time you submitted the order. Across repeated trades and larger positions, execution improvements can materially affect returns.