It's also the traders shorting and covering at lower prices. The stock will continue to go through its ups and downs until FDA approval and maybe one to two quarters of reporting afterwards. Unless you are one of the smart ones who buy low and then sell on a run up, you're in for a 6 month to a one year wait.
It's possible for a surprise at closing today, but it is more likely to be Monday since the report will be in the afternoon instead of the morning. There are still investors looking for the best price to buy.
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