Most leading stocks finished lower in mixed volume Friday as 3D Systems (DDD) sank for a second day. But FleetCor Technologies (FLT) reversed higher. FleetCor rose 0.60 to 52.19 in triple its average daily volume, ending a mild two-day slide. The stock had been down as much as 2% intraday before staging a late rally and closing at the upper end of its range, a bullish sign. The provider of fuel cards to commercial vehicle fleets is just 1% off its