The 4.2% plunge in U.S. oil prices Monday was the latest sign that the dynamics shaping the biggest commodity market have changed since the crude rally began. Last year, two main forces propelled crude higher: an agreement by the Organization of the Petroleum Exporting Countries and its partners to trim production; and robust global growth that helped sop up excess supply from U.S. shale. This year, investors are wrestling with an array of factors that can move the market: Trump administration sanctions that threaten to cut off Iranian oil from global supply; simmering U.S.-China trade tensions; OPEC’s decision to raise crude output; and dwindling production from Venezuela. Additionally, President Donald Trump has been vocal about oil, tweeting on some days that prices are too high and that he is pressuring Saudi Arabia to increase production. Last week, The Wall Street Journal reported that U.S. officials are considering dipping into […]