1 An act of carrying out some form of business between two persons. 2 A business agreement or exchange. 3Any activity in which two or more persons are involved. closed transaction. A transaction that is complete, so that the actual realized gain may be calculated for tax purposes. open transaction. A transaction in which all the events have not yet occurred, and so the computation of taxes on that transaction is not yet possible. sham transaction. A transaction that will be disregarded for ta...