KARACHI– Pakistan Stock Exchange (PSX) opened the trading session in positive territory on Monday after first session of the US-Iran talks concluded in Switzerland. At the start of the first trading day of the week, the KSE-100 index gained 1,223 points, reaching the psychological level of 180,500 points. The market had closed lower last week, with the KSE-100 index declining by 2,475 points to settle at 178,922 points. During the previous session, the index recorded an intraday high of 182,185 points and a low of 177,836 points.