Shares of Southwest Airlines Co. LUV dropped 4.2% toward a three-month low in premarket trading Wednesday, after the air carrier said it booked record revenue for the Labor Day weekend, but said close-in leisure bookings in August were on the lower-end of expectations. The company lowered its outlook for third-quarter revenue per available seat mile (RASM) to a year-over-year decline of 5% to 7% from previous guidance for a decline of 3% to 7%. Southwest also raised its fuel cost per gallon guidance range to $2.70 to $2.80 from $2.55 to $2.65, but kept its capacity outlook unchanged at up about 12%. “Managed business…
