Exchange-traded funds (or ETFs) are open ended investment companies that can be traded at any time throughout the course of the day. Typically, ETFs try to replicate a stock market index such as the S&P 500 (e.g., SPY), but recently they are now replicating investments in the currency markets with the ETF increasing in value when the US Dollar weakens versus a specific currency, such as the Euro. Certain of these funds track the price movements of world currencies versus the US Dollar, and increase in value directly counter to the US Dollar, allowing for speculation in the US Dollar for US and US Dollar denominated investors and speculators.