Yes, I think your suggestion that computer trading is likely responsible for the volume sounds right. I was taking a stab at explaining the wild swing.
Biotechs are in the spotlight now and there is a lot of debate about whether the market is in bubble territory. All biotechs are swung by ETF movement; what I call dumb money. Many biotech stocks I own have been trading erratically without much connection to changing fundamentals.
My guess is today's action was not caused by someone acting on substance.
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