Under GAAP, the fair value of an asset is the amount at which that asset could be bought or sold in a current transaction between willing parties, other than in a liquidation.

怎么审定, 谁来审定:
Quoted market price in an active market is the best evidence of fair value and is used as the basis for measurement. Many times quoted market prices for an asset are often unavailable, so an estimate of fair value can be used. As a result, difficulties can occur when making estimates of fair value.
基本上是说现在业界也没有一个统一的共识, 定价标准一般参考市场上类似交易的定价这样.

另外FASB也在推行这个方法.

当然, 最后把关的还是审计师, 付钱给他们总是要做事的...但是现在这种情况下, 数据信息不够, 他们多办也就给个"not qualified opinion"就了事, 投资者还是要自己靠自己.