Devaluation Mechanics
Currency = Bond: The Equivalence
“Since a debt asset is the promise to receive a specified amount of currency at a future date, debt and currency are essentially the same thing. If you don’t like the currency, you must not like the debt asset (e.g., bonds), and if you don’t like the bonds, you must not like the currency.” — a-00066
Practical implication: You cannot be bearish on a currency while bullish on that country’s nominal bonds (or vice versa). They are the same underlying claim. If you expect devaluation, you should also expect bonds to underperform — or demand a yield premium to hold them.
Rate Cuts → Currency Depreciation
“Mechanically, pushing down interest rates usually causes the currency to sell off. Usually, all else equal, lowering an interest rate won’t change investors’ long-term expectations of the value of a currency. If you are getting less interest in the meantime because interest rates fell, the new deal is strictly worse for the investor holding that currency.” — a-00083
Transmission: Lower rates → lower carry → holding the currency is a worse deal → sell currency. This is why CB easing and currency depreciation go together — especially when the market doesn’t believe the rate cut will produce growth (stagflation scenario).
Devaluation as Debt Reduction
“The most important thing for currencies to devalue against is debt. That is because the goal of printing money is to reduce debt burdens. Debt is a promise to deliver money, so giving more money to those who need it lessens the debt burden.” — a-00143
Debtors gain; creditors lose. Inflation/devaluation is a hidden transfer from savers to debtors. Governments with large domestic-currency debt have a structural incentive to allow inflation — it reduces the real value of their obligations.
Capital Flow Dynamics in Devaluation
Capital flows are more important than trade flows for exchange rate determination: a-00189
“Capital flows—both within countries and among them—are typically the most important flows to watch because they are the most volatile and have the biggest impacts on exchange rates and asset prices.” — a-00189
In EM devaluation crises, the sequence: a-00190
- Capital inflow reversal triggers currency crisis (not trade deficit per se)
- Monitor: portfolio flows, FDI, banking sector cross-border credit as leading indicators
EM Currency Crisis Reversal
“The top-reversal/currency-defense occurs when the bubble bursts—i.e., when the flows that caused the bubble and the high prices of the currency level, the high asset prices and the high debt growth rates finally become unsustainable. This sets in motion a mirror-opposite cycle from what we saw in the upswing.” — a-00192
The mirror dynamic: Capital inflow reversal → asset price decline → economic deterioration → more capital outflow → currency collapse. As powerful in reverse as in the original bubble.
Defense options (in order of cost):
- Raise rates (attracts capital but damages economy)
- Draw down FX reserves (buys time but unsustainable)
- Capital controls (politically toxic; often tried and failed)
- Let the currency go (inflationary but ends the crisis)
Most successful resolutions involve option 4 + simultaneous fiscal adjustment.
Currency Depreciation as Adjustment Mechanism
“Unlike a family, a country can change the amount of currency that exists, and hence, its value. That creates an important lever for countries to manage balance of payments pressures.” — a-00193
Currency depreciation corrects current account deficits: devaluation makes exports cheaper and imports expensive, restoring competitiveness. The existence of this lever is the key reason sovereign debt crises are more manageable than household debt crises — governments can adjust the price of their obligations. Countries with hard-currency debt (EM FX debt in dollars) lose this lever and face the household problem instead. — a-00193
QE → Currency Depreciation Linkage
“Mechanically, pushing down interest rates usually causes the currency to sell off. Why? If you are getting less interest in the meantime because interest rates fell, the new deal is strictly worse. The way to make the new deal fair again is for the spot currency to fall.” — a-00246
When CBs buy bonds (MP2/QE), compressed yields make local currency assets less attractive — the currency depreciates to restore return equivalence for foreign investors. Lower yield + lower currency = same total return as higher yield + stable currency. This is the mechanism by which QE/monetization transmits to FX depreciation and ultimately inflation. The full transmission chain: CB prints → buys bonds → yields fall → currency sells off → import prices rise → domestic inflation. — a-00246