In key news on UK stocks, BP PLC ( GB:BP ) shares fell by nearly 4% after the oil and gas giant warned of up to $2 billion of impairment charges in its second-quarter trading update. This also includes charges associated with the ongoing review of BP's Gelsenkirchen refinery in Germany. The company further stated that it expects weak refining margins and oil trading performance, which will impact its Q2 earnings by $500-$700 million.