Magoohi - think about it like a balance scale. If the bid side is heavier than the ask side (more sells or buys at the bid), the scale tips toward the bid and the ask/bid can drop as a result. On the other hand, if their is more action on the ask side, the ask/bid can rise. It is also affected by volume. If their is a lull in activity, the MMs will allow share buy orders to go through at the bid, as I just got a few minutes ago. However if their is a lot of buying activity, the bid/ask will rise. They keep stirring the pot to maintain action and generate money for themselves....They are at the helm, steering the ship in which ever direction they want...
Hope that helps,
Makamai
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