Yes you can exercise options and hold the stock if you have the money for the exercise price. I believe he sold some options/shares in order to exercise the majority of his options to hold as shares. (there also may be tax consequences of exercising options in the money?) Because MB is no longer an insider and is not reporting his trades ultimately we don't know what he is doing. I personally believe he is holding a large portion of his shares because he would know the potential of Poet.