If you're trading forwards or futures, be sure to include the costs of continuously rolling over your positions: you pay the bid-ask spread AND the commissions, on each and every roll.Quote from cnms2:
I like the Seamless Continuous Trading (SCT) concept that replaces entry / exit thinking with hold / reverse thinking (when it starts raining put on your raincoat, when it stops take it off). I wonder how you calculate your risk under SCT. How do you size your position?
I'll mention the fourth-best and the third-best ways to size positions in this context, and leave it to your own ingenuity and experimentation to find the best and second best methods:
4. Trust that your broker and the exchange have set the margin requirement to a reasonable value. Then positionsize = K * YourAccountValue / MarginRequirement . You choose a value for K that suits your personal risk tolerance profile.
3. Trade one share / contract / parcel, for every D dollars in your account. Positionsize = (1/D) * YourAccountValue. You choose a value for D that suits your personal risk tolerance profile.
nononsense, this is the experience of one of the Kelly criterion users ...