Bid-ask spread

Example

Say stock A is quoted at $10.00 bid and $10.05 ask, and stock B at $200.00 bid and $200.05 ask. Both spreads are 5 cents, but that is 0.5% of A’s price and only 0.025% of B’s, so relative to the money invested, a round trip in A costs twenty times as much as in B. In thin pre-market trading, A’s spread could widen to 20 cents, or 2%.

Hypothetical numbers, for illustration only.