The introduction of fair value accounting for stock options has required private companies to apply stock option valuation methodologies that were designed to be applied to their public counterparts. The two recommended methodologies, the Black-Scholes formula and the Binomial Lattice model, require the valuator to provide an input for estimated volatility; for private companies that do not have a trading history there is limited guidance regarding the determination of volatility, which results in diverging and incorrect estimates. Based on a sample representing 178 companies who filed and...