Any time you place a trade order you are making a request which automatically grants some control over those shares to whoever would be executing the trade for you. That's it. However, it's a move that's giving you control at the time the order is in play. Control you didn't have when the shares are just sitting in a database, which is the whole point. Scottrade has claimed, in the past at least, that they don't loan inactive shares for the purpose of short selling, but they are surely a minority amongst those allowing easy or at least mostly unrestricted trading of penny stocks.