Mumbai, May 7 -- Key equity benchmarks closed marginally lower on Thursday after a volatile session marked by weekly Sensex derivatives expiry and profit booking at elevated levels. The benchmarks swung between gains and losses amid mixed global signals, although broader indices outperformed on rising optimism over a potential U.S.-Iran peace agreement and easing geopolitical tensions. Softer crude prices, with Brent slipping below the $100-per-barrel mark, along with a firmer rupee against the dollar, helped cushion downside pressure and supported overall sentiment. Investors also tracked a fresh wave of Q4 earnings announcements for directional cues. The Nifty ended below the 24,350 level, weighed down by weakness in IT, FMCG and consum...