This is my understanding of how this works: When you instruct GS to sell the share for you, GS actually went to the open market and just sell the share. They

This is my understanding of how this works: When you instruct GS to sell the share for you, GS actually went to the open market and just sell the share. They are supposed to deliver the share at some time later, when they have found the share to borrow. However, they can do nothing and wait for the deadline to come. If the price drops, they will buy a share to deliver the previous sell order, and make a new sell order at the same price to "extend" the delivery deadline.