Currency-peg attack

A currency-peg attack is coordinated selling pressure against a fixed or managed exchange rate intended to exhaust the defending authority's reserves and force devaluation or abandonment of the peg. The peg converts a currency into a fixed target: the defender publicly commits to a price it must buy at, and an attacker with sufficient capital can test whether the commitment or the reserves give way first. As a warfare instrument it is the market-tempo form of coercive currency manipulation; most documented attacks, however, have been profit-driven private speculation, and the attribution of state intent in particular episodes is contested.

Mechanism

The attacker sells the pegged currency spot and forward, borrows it to short it, and positions in derivatives that pay on devaluation. The defender must buy its currency with finite reserves, raise interest rates to punitive levels, or impose controls, each defence carrying domestic economic costs that themselves feed expectations of collapse. The academic literature formalises this: first-generation models show pegs inconsistent with domestic policy collapsing under reserve exhaustion, and second-generation models show self-fulfilling attacks succeeding against pegs that were otherwise sustainable, because the cost of defence rises with the attack itself. For a state attacker the implications are attractive: a vulnerable peg can be broken deniably, through market channels, with the damage amplified by genuine speculators piling in behind the initial pressure, an amplification dynamic matching the Economic Kill Chain's fifth phase.

Employment history

The canonical demonstrations are private. On Black Wednesday and the ERM crisis, 1992, speculative pressure led by hedge funds forced sterling out of the European Exchange Rate Mechanism despite Bank of England intervention and emergency rate rises. In the Asian financial crisis of 1997 to 1998, successive pegs from Thailand outward collapsed under speculative attack. Malaysian Prime Minister Mahathir Mohamad blamed George Soros and speculative conspiracy for the ringgit's collapse; the attribution is contested and is treated as such throughout this encyclopedia, with most economists locating the causes in underlying fragility rather than directed attack (Malaysia's capital controls and exchange-rate defence, 1998-1999). Verified state employment of a peg attack as a warfare instrument is scarce in the open literature; the nearest documented analogue is the Suez sterling pressure of 1956, applied by official rather than market means. The gap between theoretical potency and thin verified state practice is itself analytically significant and is flagged rather than filled here.

Effects and countermeasures

A broken peg delivers Disrupt and Degrade effects: devaluation, inflation, balance-sheet damage where debts are foreign-denominated, and political humiliation of the defending government. Defences include large reserve war chests, credible flexible-rate regimes that remove the fixed target, allied swap lines, and capital controls, Malaysia's 1998 controls being the reference case of a state simply closing the battlefield. Hong Kong's 1998 equity-market intervention against the "double play" on its peg and stock market showed an activist defence succeeding. For prospective state attackers the constraints are attribution risk, the capital scale required against well-reserved targets, and contagion that may harm the attacker's own interests.

See also

FX shorting and speculative attack · Black Wednesday and the ERM crisis, 1992 · Malaysia's capital controls and exchange-rate defence, 1998-1999 · Coercive capital controls · Economic statecraft

Sources

• Krugman, A Model of Balance-of-Payments Crises, accessed 30 July 2026.
• Obstfeld, Models of Currency Crises with Self-Fulfilling Features, accessed 30 July 2026.
• HKMA Annual Report 1998, accessed 30 July 2026.
• IMF, Malaysian Capital Controls, accessed 30 July 2026.