Does an option to purchase stock transfer ownership to the beneficial owner of the company when the option is exercised?

An option to purchase stock does not transfer ownership until such time as the option is exercised. See Walker v. C.I.R., 544 F.2d 419, 422 (9th Cir.1976) (seller held to be the beneficial owner of stock and responsible for taxes on a dividend which was declared earlier on the same day that buyer exercised his option to purchase the stock); Danenberg v. C.I.R., 73 T.C. 370, 389-392 (1979) (beneficial ownership of stock was transferred on the effective date of the sale agreement rather than on the date the agreement was signed).