** Oil marketing companies BPCL BPCL.NS, HPCL HPCL.NS and IOC IOC.NS rise between 6% and 8%
** Nifty oil and gas index .NIFOILGAS up 2.5%
** Oil prices slide below $100 as a two-week Middle East ceasefire sparks a relief rally, fuelled by hopes that oil and gas flows through the Strait of Hormuz could resume
** U.S. President Donald Trump on Tuesday agreed to a ceasefire with Iran, less than two hours before his deadline for Tehran to reopen the strait or face devastating attacks on its civilian infrastructure
** Lower oil prices boost margins for oil refiners, while weighing on upstream oil firms like ONGC ONGC.NS and Oil India OILI.NS, which are down more than 3.5%
** YTD, HPCL and BPCL down 29% and 22%, respectively; IOC down 15%
(Reporting by Urvi Dugar in Bengaluru)
((UrviManoj.Dugar@thomsonreuters.com;))