FAS 157 requires that fair values be based on the perspective of a "market participant." Consideration of the market participant's viewpoint in fair value estimates is not new; the use of market-participant assumptions is mandated in Statements 141, 142, and 144. For example, when determining fair value in the context of an impairment, both Statements 142 and 144 provide for the use of market participant assumptions when that information is "available without undue cost and effort." Otherwise, an entity's own assumptions may be used.
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