The reality of movement like that of AYR is that when a stock reaches a certain point (such as a 52 week high), speculators, both institutional and individual investors, pile on, taking the stock to unsustainable levels. Then, when something extraneous happens, such as a renewal of the European bond crisis some other international event, or anything else for that matter, there is a mad rush for the door first by the recent speculators and then by the investors (who likewise lose their nerve). That's where you get those sharp spikes.
I try to have some exit strategy to avoid this scenario. Maybe I lose some profit, but I do all right by this strategy. So I start to lighten my portfolio methodically as the stock rises above where I thing it should be.
Of course, if something out of the ordinary happens, such as a buyout, I feel like a fool!