Let's assume I own a position in a stock and I trade with IB. Now, I would not mind owning more stock but at a lower price. Let's assume I sell a Jan put at $ 20/sh for $ .70, and the stock falls to $ 19.90/sh on expiration. Assuming I don't do anything, would I end up owning 100 shares more of the stock and paying $ 20/sh? If you say no, what about if the stock fell to $ 19/sh?