The Monetary Authority's Yam revised interbank trading rules to boost liquidity in the banking system, making it harder to manipulate local-dollar interest rates.
In these days of collateralised-debt obligations and residential mortgage-backed securities, there is no textbook to tell central bankers exactly what to do when liquidity in the interbank market dries up.
The British Bankers' Association said the interbank cost of borrowing overnight had fallen - a day after interest rate cuts and governments provided additional liquidity.