Natural gas prices have been in a significant down trend since the middle of last year. A popular method of trading natural gas, the United States Natural Gas Fund (UNG) has gone from a high of over $30 to 52-week lows of around $6.50. However, a large options spread could suggest gas prices are set to rebound in the second half of this year. A trader bought a call spread 15,000 times that will profit if UNG is substantially higher by October expiration.