Results of Kelly [5] and Breiman [2] relating optimal growth rates for gamb
ling and investing to information distances are generalised to include retu
rn distribution?; for virtually any type of game or asset. These results ar
e achieved by first introducing the notion of the optimal financial derivat
ive instrument for a given gamble or investment and then solving the relate
d optimisation problem. For assets varying continuously over time. a formul
a fur optimal dynamic portfolio adjustment follows for commonly occurring m
odels, assuming no transaction costs. The latter results are applied to ass
ets with normal and lognormal returns. The results for these are demonstrat
ed using simulation.