In contracts that contain conditions that must be satisfied after the agreement is signed and dated but before it can become effective, the closing date is sometimes referred to as the date when these conditions precedent are satisfied and the transactions contemplated by the agreement are finally completed.
The date of execution and thus the actual transfer of ownership of shares in the case of a share deal or of assets in the case of an asset deal is referred to as closing. Several weeks, or even months, may pass between signing and closing.