If you want to trade a currency you don’t already have, there are many ways to do so. There are several different kinds of contracts you can harness to invest in currencies you don’t own. For example, you could trade the euro without owning it by buying or selling options that involve the currency. Call and put options on EUR/USD would provide methods to trade the common currency’s exchange rate with the U.S. dollar.
In addition, purchasing spot contracts or forward contracts involving your currency of choice would also provide exposure.