Most central banks manage inflation and output by hiking or cutting baseline borrowing rates. The Monetary Authority of Singapore (MAS) operates completely differently. Because Singapore's domestic gross exports and imports total more than 300% of its gross domestic product, foreign exchange fluctuations transmit immediately into consumer prices.
MAS targets the Singapore Dollar Nominal Effective Exchange Rate (S$NEER). Instead of targeting interest rates, MAS guides the S$ against a trade-weighted basket of currencies belonging to its major commercial partners. The exact weights and components of this basket remain a closely guarded state secret to discourage speculative attacks on the trading floor.
The central bank manages this mechanism around three primary parameters:
- The Slope: Dictates the rate at which the policy band appreciates or depreciates over time to combat imported inflation.
- The Midpoint: The center axis around which the currency basket is allowed to fluctuate day-to-day.
- The Width: An undisclosed upper and lower boundary (estimated by analysts at roughly 2% on either side) that accommodates transitory market volatility without triggering direct central bank intervention.
When the S$ threatens to pierce the ceiling or floor of this invisible corridor, MAS enters the open foreign exchange market, buying or selling foreign assets to steer the currency back into the band.
