I've been trading SPY for awhile now with some success. I like the liquidity but don't like the low beta. Some of the stocks I trade such as FSLR move about 3 times as much as the SPY. I was wondering if it was possible to trade an ultrashort index which is indexed to twice the inverse movement of the market simply for the added leverage. Can you short an ultrashort index also? Are there any with good liquidity of at least a few hundred thousand shares daily?