(17)A risk may evolve over time and, in order to adapt to the evolution of the risk, commodity or emission allowance derivatives initially executed for reducing risk related to commercial activity may have to be offset through the use of additional commodity or emission allowance derivative contracts. As a result, hedging of a risk may be achieved by a combination of commodity or emission allowance derivative contracts, including offsetting commodity derivative contracts that offset those commodity derivative contracts that have become unrelated to the commercial risk. Additionally the evolution of a risk that has been addressed by the entering into of a position in a commodity or emission allowance derivative for the purpose of reducing that risk should not subsequently give rise to the re-evaluation of that position as being not a privileged transaction ab initio.