This paper examines the measurement of non-financial assets in imperfectly competitive markets and considers the effect of alternative measurements on firms' investing and operating activities. We analyze a duopoly where each firm manufactures, reports, and thereafter sells its inventory. We initially characterize the informativeness of a firm's accounting report when it is prepared using historical cost and find a firm's report does not always reveal its level of inventory. We then characterize the informativeness of a report when it is prepared using fair value and find it completely reveals a firm's inventory holding. We highlight the difficulty of implementing fair value measurements that arise because fair value is an endogenous consequence of the strategic interaction between firms.