After a few years at a start-up, I left and purchased all the incentive stock options I had vested. The company is still not public, but I have physical "common stock" certificates. Now what do I do? How important are the physical certificates? If the company does go public, what do I do? Do I give the certificates to a broker? Can I mail them to someone to put in a safe deposit box without fear of losing them? Are they bearer? I'm clear on all the AMT business, I just need to know what to do with these things.