ProShares Ultra Euro seeks daily investment results, before fees and expenses, that correspond to two times (2x) the daily performance of the price of the euro versus the U.S. dollar.
ProShares UltraShort Euro seeks daily investment results, before fees and expenses, that correspond to two times the inverse (-2x) of the daily performance of the price of the euro versus the U.S. dollar.
DDR seems to have ceased trading in April 2020.
- Note that these were unsecured debt securities issued by Morgan
Stanley. When you buy an ETN issued by Morgan Stanley, you must be confident about the credit-worthiness of Morgan Stanley. If Morgan Stanley goes bust, you might lose your investment regardless of what actually happens to the actual USD/EUR exchange rate.
As you can see, both ULE and EUO only claim to track the movement of the Euro over a period of one day. They are not designed to be held for more than one day, and you may incur losses for doing so.
If your grandparents want to hold for a period greater than one day, they could:
Find a reputable forex broker that allows shorting the USD/EUR pair, or
Buy puts on a normal long ETF that track USD/EUR movements, or
Buy puts on USD/EUR futures, or
Enter into a USD/EUR futures contract.
Just make sure you know what you are getting into when playing with shorts and/or derivatives.