Don't you think that there would be a lot of traders taking profits after three massive up days? Maybe some pre-market news spooked them? That would surely bring the stock down as the market opens. Other traders with steadier motivation and a longer time frame will take advantage of that and the market recovers.
A good general rule is to not trade the first 30-minutes unless you have a plan ahead of time that takes advantage of the chaos that often emerges then.
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