How are stock options treated in divorce?

Vested stock options are marital assets, as are pensions. Stock options not yet vested or matured are treated differently, and are up for negotiation.  Unvested stock options are awarded to encourage a good employee to stay with the company.  That is why they vest at a later period in time.  

Some spouses accept a "buy out" of their right to receive a portion of the options (their "marital share," or half the value of any options received during the marriage) when they vest.  Sometimes, the spouse with the unvested options may successfully argue that they are not a marital asset because there is no guarantee they will be received, and as such, it would be unfair to have to pay their spouse for something the party with the unvested option may never get.  Or, they may agree to give the other party a different asset simply to take the unvested options off the negotiation table.