min order size to show on l2, which they have been testing. For example if you put a bid for 2000 shares for 49c, the MM will not move the price up to 49c, unless they have other orders. You order will be filled whenever the price moves down and hits that MM's price on l2 (or if the ask moves down to 49c). You can of course avoid this by buying off the ask or moving your bid up to 2500. Though I have found, a MM will fill you for say 100 shares, and your bid drops back off again (which is frustrating to say the least). At 51c, the 2000 share bid order will show on l2.