Standard and Poor's announced a change to its Principal Stability (money fund) ratings, allowing exclusion of Federally guaranteed student loans from S&P's "illiquid basket" criteria. The company says all extendible asset-backed CP (XABCP) should be "illiquid" unless a list of criteria is met. Money Fund Intelligence, which lists AAA ratings, says triple-A's account for almost 40% of all money fund assets.