Stock valuation

[Guest slt]

I was wondering if anyone could tell me their practices with respect to how frequently they value stock under an executive comp plan? I have an ISO plan and a non-qualified stock option plan (not a 423 plan) and regularly have annual valuations by an outside appraiser conducted to determine the fair market value of stock issued under these plans. With respect to ISOs, I know the stock must be granted at its fair market value on the date of grant. In theory, if I had a number of corporate events occur after I valued my stock and I granted additional ISOs using a value I ascertained 6 months ago during my annual valuation, aren't I in danger of having my ISOs recharacterized as NQSOs? But my main question is how often are people out there valuing their stocks? Annually? Quarterly? Thanks so much everyone!