Why does the negative value in my inventory increase each time a customer pre-orders?

Question: I am quite confused with the way the negative value in my inventory updates. When a customer pre-orders a product, and the order is created, the negative value of that product's inventory increases instead of decreasing. Why is this so?

Before an order is created:

After an order is created:

Answer: The negative value in your product's inventory indicates the number of orders that are already created when the product is out of stock, and not how many pieces of the item is in-stock. Since the product is currently not available, it is expected for the negative value to increase each time a new order for the item comes in. This value helps you identify right away how many orders of the item need to be filled in.