Washington

THE US Treasury Department's debt-management unit likes sticking to one rule: Don't surprise the market. The Federal Reserve is about to make that task trickier.

For years, the US central bank has been the Treasury's best customer, accumulating US$2.46 trillion in US debt through its cash injections aimed at stoking a recovery from the worst recession since the 1930s. That's about to change as the Fed prepares to raise interest rates from near-zero, followed by a planned decision to let its balance sheet shrink at some point.