You want to make money as market maker for used iPhone 14, which currently worth around $800. After testing the water, you discover the following patterns. If you set the bid-ask spread to $100 (e.g. buy at $750 and sell at $850), you can flip around 100 phones (buy 100 and then sell them). If you set the bid-ask spread to $200, you can flip around 60 phones. Should you set the bid-ask spread to $100 or $200? For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 (Mac).