A nuclear deal between Iran and countries including the U.S. and Russia could prompt sovereign upgrades of Persian Gulf Arab nations even as it may cut their revenue by causing oil prices to fall, according to IHS Inc. “The reduction in geopolitical risk would serve as a key trigger for a sovereign ratings review for the countries of the Gulf Cooperation Council, and potentially an upgrade,” Bryan Plamondon, an economist specializing in the Middle East at energy consultant IHS, said yesterday by e-mail from Lexington, Massachusetts . “Countries would then likely see benefits in the form of lower borrowing costs and greater foreign investment.” Talks between Iran and the so-called P5+1 group of world powers resumed yesterday in Geneva. “Differences that remain between the parties are narrow, and I believe they can be bridged with political will and commitment,” U.K. Foreign Secretary William Hague said in the city. Concern […]