Why does a big order get a worse price than a small one?
A retail order for shares fills right at the quoted price, but an institution trying to move shares gets a visibly worse average price, and a dealer asked to quote a large block quotes a much wider spread than the screen shows.
Why does size earn a worse price? Tie your explanation to the components of the spread.
Show a hint
Spread = adverse selection + inventory risk + processing costs. Both of the first two scale with order size.
Your answer
This one is open-ended. Work it through, then check your reasoning against the full solution.