On the other hand, certain financial techniques can reduce the impact of such purchases on the currency. One is sterilisation, in which highly valued assets are sold at the same time that the weaker assets are purchased, which keeps the money supply neutral. Another technique is simply to accept the bad assets as long-term collateral (as opposed to short-term repo swaps) to be held until their market value stabilises. This would imply, as a quid pro quo, adjustments in taxation and expenditure in the economies of the weaker states to improve the perceived value of the assets.