Legislative and executive branch policymakers should carefully consider curbing investment portfolios of the Federal Home Loan Banks, say former Bank officials, while a current top Bank official says any such changes in the FHLBanks’ investment authority could undermine the system’s ability to carry out its mission.Since 1990, when Congress broadened the FHLBanks’ previously restricted membership, the pressures for dividends, price competition for advances and increases in required capital levels have significantly increased the “investment” portion of the Banks’ balance sheets, according to former Federal Housing Finance Board Chairman Bruce Morrison.