Oil futures drop as natural-gas prices rally

SAN FRANCISCO (MarketWatch) -- Oil futures closed lower on Monday, giving back most of what it gained in the previous session as traders factored in the potential for more supply from Iran following the country's nuclear deal with Western powers. Natural-gas futures rallied, rebounding after last week's loss. February crude fell 92 cents, or 1%, to settle at $91.80 a barrel on the New York