If your husband used separate funds generated by his separate property to purchase stocks that he also maintains as his separate property, and in which he is a passive investor, he would have a plausible case that the stocks are his separate property. It is possible that active management of separate property during marriage or the maintenance of the property based upon the expenditure of marital assets will cause the property (or some portion of the property or increased equity) to become part of the marital estate. The devil is in the details, so discuss the details with your divorce lawyer.
If your husband receives a gift or inheritance, that is typically also treated as separate property with the same qualifications as described above.

