Books published through the IngramSpark platform are printed as they are ordered (Print On Demand). Ingram's stock check app and iPage will reflect a virtual "in-stock" inventory, so your book always appears available for ordering to bookstores, libraries, and retailers, who may not order a book that doesn't appear as in stock. The number of copies listed as "in-stock" is meant to establish conceivable availability requirements, not represent actual inventory.
Because we don't stockpile Print on Demand content, the benefit of virtual inventory is that retailers and channel partners see your book as available to order. This helps ensure that self-published content looks as equally available for purchase as any traditionally published title would appear.
The specific quantities displayed as virtual inventory vary in part to protect the self-published content from retailer prejudice against Print on Demand content, and Ingram will adjust this number based on a number of factors, including recent demand for the title.