As an absolute rule of funders, each of them wants to see a positive working capital because positive working capital implies there are sufficient current assets to meet current obligations. In contrast, companies risk being unable to meet current obligations with current assets when working capital is negative. While it's theoretically possible for a company to indefinitely show negative working capital on regularly reported balance sheets (since working capital may actually be positive between reporting periods), working capital will generally need to be non-negative for the business to be sustainable