Definition
What is 409A valuation?
A 409A valuation is an independent appraisal of a US private company's common stock, used to set the exercise price of employee stock options so they aren't treated as discounted for tax purposes.
Companies typically refresh it at least yearly and after each priced round or material event. It is a US concept; other countries have their own rules for option pricing.
General information, not legal, tax or investment advice.