Financial statements prepared in accordance with generally accepted accounting principles (GAAP) show many assets based on their historic costs rather than at their current market values. For instance, a firm's balance sheet will usually show the value of land it owns at what the firm paid for it rather than at its current market value. But under GAAP requirements, a firm must show the fair values (which usually approximates market value) of some types of assets such as financial instruments that are held for sale rather than at their original cost. When a firm is required to show some of its assets at fair value, some call this process "mark-to-market". But reporting asset values on financial statements at fair values gives managers ample opportunity to slant asset values upward to artificially increase profits and their stock prices. Managers may be motivated to alter earnings upward so they can earn bonuses. Despite the risk of manager bias, equity investors and creditors prefer to know the market values of a firm's assets—rather than their historical costs—because current values give them better information to make decisions.