LOL a MM never shows his actual bid or ask sized because that works against them. But if it is a retail order they have to show the size! It is call not showing one's hand and it would be counterproductive to let the market know the size he is trying to sell or buy, unless he is trying to bluff to move the price in his direction. It is like playing poker no one wants to show their hand, but one can often gauge what is actually happening by the 10,000 share size transactions being shown and the trades going off while those bids and/or ask sit there with 10,000 share size, while transactions are going off.
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