The S&P 500, the major market index with the most exposure to the oil and gas sector, was set to open higher after a weekend of geopolitical upheaval, with President Donald Trump declaring that the U.S. plans to “run” Venezuela following the capture of its longtime leader Nicolás Maduro. Oil stocks, including Chevron, Valero, and ConocoPhillips, were leading the early gains. But even as stocks rose, gold was flirting with record highs, with silver climbing even more dramatically. The split-screen market ...