Transaction costs are the main hindrance to the active or tactical
asset allocation process. The transaction cost has to be paid for
whether the investor is buying or selling to accomplish a ****ft in the
asset mix of his ****tfolio.
The investor can do the same buying (calling) and selling (putting)
through futures to accomplish the same changes in the asset mix of his
****tfolio.
A further exposition for a better understanding maybe read at:
http://www.narachinvestment.com/using_futures_in_asset_allocation.htm
(You may click on the link above or type the complete URL address into
your browser)