Airlines stocks fell as fuel prices rose. United Continental Holdings, the world’s biggest airline, fell 9.1 percent. Delta Air Lines lost 78 cents, or 7.2 percent, to close at $10.05. And US Airways Group saw the biggest decline percentage wise, closing down $1.01, or 11.35 percent, at $7.89. Jet fuel is the single biggest expense for most airlines. As of last week the price had risen 12 percent over the past year.