Flexible exchange rates can be defined as exchange rates determined by global supply and demand of currency. In other words, they are prices of foreign exchange determined by the market, that can rapidly change due to supply and demand, and are not pegged nor controlled by central banks. The opposite scenario, where central banks intervene in the market with purchases and sales of foreign and domestic currency in order to keep the exchange rate within limits, also known as bands, is called fixed exchange rate.
Within this pure definition of flexible exchange rate, we can find two types of flexible exchange rates: pure floating regimes and managed floating regimes. On the one hand, pure floating regimes exist when, in a flexible exchange rate regime, there are absolutely no official purchases or sales of currency. On the other hand, managed (also called dirty) floating regimes, are those flexible exchange rate regimes where at least some official intervention happens.
Flexible exchange rate regimes were rare before the late twentieth century. Prior to World War II, governments used to purchase and sell foreign and domestic currency in order to maintain a desirable exchange rate, especially in accordance with each country’s trade policy. After a few experiences with flexible exchange rates during the 1920s, most countries came back to the gold standard. In 1930, before a new wave of flexible rate regimes started, prior to the war, over 50 countries were on the gold standard. However, most countries would abandon it just before World War II started.
In 1944, with the war almost over, international policy coordination was starting to make sense in everybody’s mind. Along with other international organisations created during those years, the Bretton Woods agreement was signed, putting in place a new pegging system: currencies were pegged to the dollar, which in turn was pegged to gold. It was not until 1973, when Bretton Woods completely collapsed, that countries started to implement flexible exchange rate regimes.
Milton Friedman was a great advocate for floating exchange rates. In his article “The Case for Flexible Exchange Rates”, 1953, he pointed out the extent to which flexible exchange rates would improve the global economy, by means of monetary independence. Also, economists Robert Mundell and Marcus Fleming, as demonstrated by the IS-LM-BoP model that derives from their works, pointed out how hurtful fixed exchange rates can be. All this relates to the “impossible trinity” concept.
The following figure shows the different regimes according to four different variables: exchange rate flexibility, loss of monetary policy independence, anti-inflation effect and credibility of the exchange rate commitment: