In economics, a speculative attack is a precipitous acquisition of some assets (currencies, gold, emission permits, remaining quotas) by previously inactive speculators. The first model of a speculative attack was contained in a 1975 discussion paper on the gold market by Stephen Salant and Dale Henderson at the Federal Reserve Board. Paul Krugman, who visited the Board as a graduate student intern, soon adapted their mechanism to explain speculative attacks in the foreign exchange market.