What it means
A rate cut lands and the currency plunges 8%, then recovers half within months. The plunge was not the destination; it was the journey, and overshooting explains why.
Rudiger Dornbusch built the theory in 1976, and his Journal of Political Economy paper, Expectations and Exchange Rate Dynamics, showed how sticky goods prices force currencies to overreact to monetary shocks. The logic runs through interest rates: a policy change shifts the return on holding a currency, and because goods prices cannot jump to compensate, the exchange rate jumps instead.
The jump must overshoot to balance, since if the currency fell only to its new long-run level, interest differentials would stay unbalanced, so it falls further, creating the expectation of recovery that equalises returns. Goods prices then catch up slowly, as inflation and adjustment grind through the economy over quarters and years and the exchange rate drifts back toward its long-run value.
The theory rescued a puzzle, because floating rates in the 1970s proved far more volatile than anyone expected, and overshooting explained the violence as a feature, not a malfunction. For an importer, the lesson is patience with hedges, since the first reaction to a policy shock overstates the lasting one and panic-hedging at the extreme locks in the overshoot.
For a CFO with currency exposure, the practical rule is horizon separation: short windows after shocks show overshoot, long windows show fundamentals, and hedging policy should know which window it is reading. Central banks read it as a warning, because aggressive easing can trigger currency drops larger than intended, importing inflation through the exchange rate before domestic prices have moved at all.
Portfolio flows reinforce the pattern, as capital races into or out of a currency on the rate news and the herd's speed is part of why the first move outruns the eventual one. The model remains the benchmark, and generations of exchange-rate theories refine it, but the sticky-price core survives every empirical fashion.
The idea travels beyond currencies, since any market with fast prices and slow fundamentals can overshoot, and forecasters respect the humility it teaches, because models that ignore sticky prices chronically under-predict currency volatility.
In practice
Real-world examples.
Example
A surprise tightening sends the currency up 6% in a day. Over the next year it gives back most of the jump as goods prices adjust. The drift took a year.
Example
An emergency cut in a crisis produces a currency plunge deeper than any model's fair value. The recovery begins before the crisis ends, the overshoot unwinding first. Businesses that waited to price in the new level avoided the worst of the extreme.
Example
A finance team panic-buys foreign currency at the panic low. The overshoot reverses within a quarter, and the hedge becomes the loss it was meant to prevent. The team then adopts a written hedge ratio decided in calm periods.
Formula
Calculation
There is no single formula; the pattern is the signature: an exchange-rate reaction larger than the long-run change. A shock meriting a 4% depreciation produces an 8% drop, then a drift back over time.
Worked example. A foreign currency costs $1.00 per unit before a surprise rate cut. The long-run effect of the cut is a 4% depreciation of the dollar, which would take the rate to $1.04, but the market overshoots by jumping 8% to $1.08. An importer owing 1,000,000 foreign units would pay $1,000,000 before the shock, $1,080,000 at the overshoot peak and $1,040,000 once the rate drifts back to its long-run level. Hedging in panic at $1.08 locks in $1,080,000, which is $40,000 more ($1,080,000 - $1,040,000) than the long-run cost, and half of the 8% jump (4 points) reverses over the following quarters.Case study
Seen in the real world.
In this illustrative fictional case, Selma, treasurer of an electronics importer, sees the home currency crash 9% on an emergency rate cut. Her policy says hedge only 50% at extremes; three months later the currency has recovered half the fall, and the unhedged portion costs far less than panic cover would have. The ratio held through the storm.
Her importer owes 2,000,000 foreign units, priced at $1.00 each before the crash and $1.09 at the extreme. Hedging half at $1.09 costs $1,090,000 (1,000,000 x $1.09), and the unhedged half is bought three months later at $1.045 for $1,045,000, a total of $2,135,000. Panic cover on the full amount would have cost $2,180,000 (2,000,000 x $1.09), so the policy saved $45,000.
Watch out
Common mistakes.
- Reading the first move as the new normal, when the initial reaction overshoots by design, and policy shocks produce their largest currency effects in their first hours. Hours exaggerate the truth.
- Hedging at the extreme out of fear, when panic cover locks in the overshoot, and disciplined ratios decided in calm periods beat decisions made at the panic print.
- Assuming the pattern guarantees quick reversal, when the drift back takes quarters or years, and overshooting describes the path, not a promise about your quarter.
Questions
People also ask.
What is overshooting?
The exchange rate's habit of jumping past its long-run level after a shock, then settling back. Dornbusch explained it in 1976: currency markets move instantly while goods prices adjust slowly, so the currency overreacts. Stickiness drives the jump.
Why must it overshoot?
To balance returns. If the currency moved only to its new long-run level, interest differentials would stay unbalanced, so it moves further, and the expected drift back is what equalises the return on holding each currency. The drift back balances returns.
What should a treasurer watch?
Horizon and policy ratios. The first reaction overstates the lasting one, so hedging ratios set in calm periods should govern decisions at the extreme print, not panic.
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