The Bank sets out the objectives for investment through the development of a SAA. Following the approval of the SAA, the reserves are allocated to the various currencies and asset classes. Both internal and external fund managers are selected to build portfolios via the purchase of securities in the designated asset classes. The performance of the assets and fund managers is measured over different reporting periods to assess and monitor the risk and return efficiency of the portfolios. Performance attribution is used to explain the sources of these returns and to assess the quality of portfolio management decisions made. Investment performance measurement and attribution thus assist with assessing the effectiveness of the SAA.