I'll take a crack at it. The chart readers are convinced that there is serious technical resistance at 80. So, as it approaches 80, they short it. As long as volume is relatively weak, this will drive the price down. Remember, despite all the "breakthrough therapy" designations, we don't have an actual marketable product yet. And no one HAS to own the stock right now. I'd guess that the next real catalyst will be the release of the ASCO abstracts at the end of May. In the meantime, I wouldn't want to be out of this stock in my taxable accounts. I feel that once you've owned a stock like this for a year, it becomes much more valuable. Even if it doesn't go up. (which this one definitely has) Because any potential gains are worth twice as much as gains made via short term trading. If, for example, you own 1,000 shares @ 20, your profits of $57,000 would be reduced to $45,600 (assuming you're in a high bracket) by long term capital gains rates. But if you made the same $57,000 via trading, your profits would be reduced to $34,200. The stock would have to go down more than 11 points to make selling in less than a year a good move. This is a rough approximation and disregards state taxes. Remember, these companies don't really start to move until they begin to book actual revenues from sales.