Fortune business confidence index is a monthly survey of chief financial officers at large fortune 1000 firms. An Australia bank (NAB) business confidence Index. Managers often prefer business confidence indices to economic statistics because they know that managers make business decisions that are in line with their expectations concerning the economy's future. So if the fortune index or the NAB business confidence index in Australia are dropping, a manager might decide against hiring new employees, increasing production or taking out additional loans to expand the business.