The gross unrealized losses related to mutual funds, stocks, corporate bonds and bank debentures were  due to fair value fluctuations. The Company reviewed its investment portfolio to identify and evaluate  investments that have indications of possible impairment. Factors that were considered in determining  whether a loss is other-than-temporary included but were not limited to, the length of time and extent to  which fair value has been less than the cost basis, credit quality and the Company’s ability and intent to  hold the investment for a period of time sufficient to allow for any anticipated recovery in market value.  As a result, the Company determined that aforementioned investments with unrealized losses were not  deemed to be other-than-temporarily impaired as of December 31, 2010.  The fair value guidance requires disclosure that establishes a framework for measuring fair value and  expands disclosure about fair value measurements. The standard describes a fair value hierarchy based on  three levels of inputs that may be used to measure fair value. The level in the fair value hierarchy within  which the fair value measurement in its entirely falls shall be determined based on the lowest level input  that is significant to the fair value measurement in its entirety. These levels are:  The following table presents our assets and liabilities measured at fair value on a recurring basis at  December 31, 2009 and 2010:  Level 1: Quoted prices in active markets for identical assets or liabilities that the Company has the ability  to access at the measurement date;  Level 2: Quoted prices in markets that are not active, or inputs which are observable, either directly or  indirectly, for substantially the full term of the asset or liability; or  Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value  measurement and are unobservable.  d. Fair value measurements  Assets and liabilities measured at fair value on a recurring basis  December 31, 2009  Level 1 Level 2 Level 3 Total NT$ NT$ NT$ NT$ (In Millions) Assets Derivatives - currency swap contracts  $  —  $  7  $  —  $  7  Convertible bonds 34  —  34  Available-for-sale securities Open-end mutual funds 16,832  —  —  16,832  Domestic listed stocks 500  500  Corporate bonds —  103  —  103  Real estate investment trust 102  —  102  $  17,468  $  110  $  —  $  17,578  Liabilities Derivative - forward exchange contracts... $  —  $  1  $  —  $  1  F-77