A prenuptial agreement in California typically states how spouses would divide assets in the event of a divorce.
The couple usually waives the right to make claims based on community-property laws, which state that any property created after the marriage is essentially community property and should be split evenly after any divorce.
California is one of a handful of states with community-property laws. Most states rely on equitable-division rules, which give more flexibility to a judge in dividing assets.
In Chan's case, she could lay claim to a portion of the options and grants in Facebook stock that vest during the time of their marriage, lawyers said.
If there were no prenup, or if there were and Chan contested it, she could also try to go after stock Zuckerberg held previously if she could claim it increased in value during the relationship and the increase was due directly to Zuckerberg's efforts.
Image: Zuckerberg, right, and Chan during their visit to Shanghai.