What it means
Under a floating exchange rate, the market decides what a currency is worth minute by minute. Under a peg, the government announces a target, often against the US dollar, and instructs the central bank to keep the rate there, usually within a narrow band of a fraction of a per cent either side.
Holding that line requires the bank to stand ready to buy or sell its own currency in unlimited size at the edges of the band. Businesses generally like pegs because they remove exchange rate uncertainty from cross-border pricing and contracts.
An importer in a pegged economy can quote prices a year ahead with confidence, and foreign investors face one less risk when funding a local project. That stability is one reason several oil exporting states and trade-dependent financial centres have kept pegs for decades.
The cost is a loss of monetary independence, sometimes described as the trilemma: a country can have a fixed exchange rate, free movement of capital and an independent interest rate policy, but only two of the three at once. A country pegged to the dollar with open capital markets must broadly follow US interest rates, even if its own economy needs the opposite.
That means importing another country's monetary policy along with its currency stability. Pegs come in degrees.
A hard peg such as a currency board backs every unit of local currency with foreign reserves and is very difficult to break; a soft peg allows a wider band and periodic adjustment; a crawling peg moves the target by a small planned amount each month to accommodate higher domestic inflation. The looser the arrangement, the more room for policy and the more room for doubt.
The failure mode is well understood. If the pegged rate drifts far from what economic fundamentals justify, speculators sell the currency in size, reserves drain away defending it, and the peg eventually breaks in a sharp devaluation rather than a gentle slide.
Countries usually manage this risk by holding reserves well in excess of their monetary base and by adjusting the target early rather than defending an indefensible level.
In practice
Real-world examples.
Example
A Gulf oil exporter pegs to the US dollar so that its crude revenues, which are priced in dollars, translate into a stable domestic budget. The trade-off is that when US rates rise to cool an overheating American economy, the Gulf state must follow even while its own construction sector is slowing.
Example
A regional airline based in a pegged economy signs eight-year aircraft leases denominated in dollars without hedging, reasoning that the peg has held for twenty years. Its risk committee still requires a written scenario showing what happens to lease costs if the peg is ever abandoned.
Example
A manufacturer in a country running a crawling peg builds a 4% annual currency slide into its export pricing model. Because the adjustment is announced in advance, it can raise local wages in line with inflation without losing competitiveness abroad.
Think of it
“Currency peg is fixing your currency's value to another-a fixed exchange rate.
Formula
Calculation
Formula:
Band limits = Peg rate x (1 +/- Band width)
Reserve cover ratio = Foreign exchange reserves / Monetary base
Worked example. A small open economy pegs its currency, the marlin, at 7.80 marlins per US dollar and allows a band of 1% either side.
Upper limit: 7.80 x 0.01 = 0.078, so the weak edge of the band is 7.80 + 0.078 = 7.878 marlins per dollar. Lower limit: 7.80 - 0.078 = 7.722 marlins per dollar. Whenever trading reaches 7.878 the central bank sells dollars and buys marlins; at 7.722 it does the reverse.
Now the credibility test. The central bank holds $60,000,000,000 of foreign exchange reserves against a monetary base worth $50,000,000,000 at the pegged rate, giving a reserve cover ratio of $60,000,000,000 / $50,000,000,000 = 1.20, or 120%. Because it could in principle buy back every unit of local currency in circulation and still have $10,000,000,000 spare, the peg looks defensible, and that arithmetic is precisely what deters a speculative attack.Case study
Seen in the real world.
This example is illustrative and fictional. Vantara, an invented island economy, pegged its currency at 5.00 vantars to the dollar to attract tourism investment, and for eight years the arrangement worked well enough that hotel groups borrowed heavily in dollars.
Domestic inflation, however, ran about 6% a year while US inflation ran near 2%, so Vantara's costs rose steadily against those of its competitors while the exchange rate stayed put. By year eight a beach holiday in Vantara cost visitors roughly a third more in real terms than an equivalent holiday elsewhere, bookings fell, and the current account moved deep into deficit.
Reserves that had once covered 140% of the monetary base fell below 60% as the central bank defended the rate. Vantara's finance ministry finally replaced the fixed peg with a crawling peg that allowed a 5% annual adjustment, which restored competitiveness gradually and, in this illustrative telling, spared the country the disorderly devaluation it had been heading towards.
Watch out
Common mistakes.
- Treating a long-standing peg as a guarantee and leaving foreign currency debt unhedged, when the whole risk of a peg is concentrated in the rare day it breaks.
- Confusing a peg with a currency union; a pegged country keeps its own currency and can abandon the target, whereas a member of a shared currency has given up the option entirely.
- Assuming a pegged currency means stable prices, when domestic inflation can run far above the anchor country's and quietly erode competitiveness while the headline rate never moves.
Questions
People also ask.
Why would a country give up control of its interest rates?
Because credible price stability and predictable trade terms can be worth more to a small, very open economy than the ability to fine-tune domestic demand.
What is the difference between a peg and a managed float?
A peg names a specific target the authorities commit to defend, while a managed float involves occasional intervention to smooth movements without any promised level.
How can I tell if a peg is under strain?
Watch foreign exchange reserves falling month after month, forward rates pricing a materially weaker currency than the spot peg, and domestic interest rates being pushed sharply higher to deter selling.
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