** Shares of chemical maker LyondellBasell LYB.N fall about 2.5% to $56.50 premarket
** LYB misses Q2 profit estimates, hurt by lower margins and higher energy costs
** Posts Q2 adjusted profit of 62 cents/share vs analysts' estimate of 80 cents/share - data compiled by LSEG
** Co's olefins and polyolefins-Americas unit, its largest segment by sales volume, posts Q2 adjusted core earnings of $318 mln, down from $670 mln the previous year
** Up to last close, stock down 22% YTD
(Reporting by Pranav Mathur in Bengaluru)
((Pranav.Mathur@thomsonreuters.com;))