The XLB materials exchange traded fund has risen 50 percent since its March lows, and options traders are betting that it still has some fuel left in the tank .

More than 71,000 calls changed hands at the June 28 strike yesterday, including a single chunk of 49,900 bought for $0.90, according to OptionMonster's tracking systems. The average daily volume at that strike is just 38 calls, and open interest was 1,072 contracts.