smartest option is probably to put the money in a bond etf such as shy (short term treasury) or lqd (high quality corporates) or hyg (junk bonds), this will marginally lower the amount of leverage you can use with stocks but imo you shouldn't be leveraged with stocks outside of daytrading anyway, other options include efp's with ib but rates are pretty low right now or selling dollars to buy higher yielding currency but that is dependant on the dollar reversing lower to make money
