KARACHI: As international oil prices continued their downward movement amid ongoing Middle East de-escalation talks, bulls managed to tighten their grip over the market for the fourth straight session despite a volatile start at the Pakistan Stock Exchange (PSX) on Thursday. The market drew its strength from strong investor interest in cement scrips, followed by fertiliser, E&P and banking sectors. Topline Securities Ltd said the local bourse opened on a positive note, carrying forward the bullish momentum from the previous session as the benchmark index climbed to an intraday high of 1,569 points.