Insiders sell shares for a lot of reasons - buy a yacht, a house, pay tuition, go on vacation, buy a Lamborghini, pay taxes (keep in mind, when you execute options, taxes are due immediately), and ESPeCIALLY, diversify. All financial advisors counsel to not hold all your assets in the company that also pays your salary.
On the other hand, insiders buy shares for only one reason -- because they thing the stock is going to appreciate.
I have a very small position in CYS that I will be looking to build over the next quarter, but for today, I am buying heavy into ORC at $11.70-11.75! Finally getting the opportunity to round out my position there at the prices I wanted. I don't think CYS will get away from me before I get back to it, but I can't let go of getting in to ORC at an 18%+ yield right now, especially with insiders buying at $12.55.