BP PLC ticked up on Monday. But gains lagged Shell as traders continued to give BP a weaker read, keeping a discount in place over its higher debt load, despite oil pushing higher after new U.S.-Iran strikes. BP was at 470.60 pence, gaining 1.20p, or 0.26%, as of 08:55 BST after London opened. Shell added 13p to 2,911p, up 0.45% at the same time. BP volume stood at about 2.02 million shares, only 4% of the 65-day average. Shell saw 272,110 shares change hands, roughly 3% of its 65-day average.