U.S. energy firms this week increased the number of oil rigs operating for the first time this year but the rig count in January fell the most in a month since April 2016, as the boom in the Permian, the nation’s biggest shale oil formation, cools. Drillers added 10 oil rigs in the week to Jan. 25, bringing the total count to 862, General Electric Co’s Baker Hughes energy services firm said in its closely followed report on Friday. More than half the total U.S. oil rigs are in the Permian where active units rose by three this week to 484, well short of a near four-year high of 493 in November. […]