large spreads mean MM's are slowing the trading down. Usually to stop something from happening. That something could me many things. But if you trade long enough you will see that trading slows when spreads open up.
Possible reasons: (not a complete list but the basics) -Stop a stock from bleeding out to fast -Stop a stock from moving up too fast -Forced movement up or down for covering bad positions -Manipulation by other traders
It's an MM's job to balance the market, but some have specific agendas. So seeing which MM is on top usually tells you the reason why.
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