My guess is that it is that larger traders getting out and...

My guess is that it is that larger traders getting out and taking profit, if the fundamentals are strong enough the buyers will eventually take this resistance out and the stock should push on. It had a pretty good run from the mid forties and may take a breather before pushing on. I had a bid on at 60 but then took it off after having second thoughts.
AWE looks like a better candidate for more upside in the short term imo, I could easily be wrong and hope they both go up.
HDR is a great story, but also seems to be a favorite amongst the traders whose wisely seek liquidity, so one must be cautious and be prepared to sit on a loss for awhile if you are unfortunate enough to buy a short term top and left sweating out a loss straight away.
I dont own HDR, and would be looking for a buy at lower prices.