Managed Futures return calculation

CAIA
#1

Kaplan says that.

" unlike traditional assets, where real returns are based on real cash positions, returns for futures portfolio may involve offsetting and leveraged positions, which are used both for hadging and trading. These positions complicate the return calculation"

I don’t know why it’s so hard to calculate futures return based on the statement above. any thought?

" Unlike forward investors, futures investors post collateral to cover daily losses. This difference makes comparing futures returns with the returns of other assets more difficult."

Why posting collateral makes return calculation for futures become more difficult

thank you!

#2

Posted margin and dedutible cost offset return from manged future.

one condition that managed future is not zero sum is to have a cash position with managed future position