A partial fill occurs in the following scenarios:
1. Your bid met the clearing price, but couldn’t be fully executed because there weren’t enough shares for sale.
2. Your ask met the clearing price, but couldn't be fully executed because there weren't enough buyers.
The remainder of your trade will remain pending, and get executed next time it meets the clearing price. If you want to submit at a new price or quantity, you may cancel your trade and submit a new one at any time.