Investors are finally taking record U.S. oil stockpiles seriously. Oil slumped the most in more than a year after government data showed production cuts from OPEC and other exporters have not been enough to reduce U.S. supplies. Saudi Arabia’s Oil Minister Khalid Al-Falih said in Houston Tuesday that global supplies have been slower to decline than OPEC and its partners expected, leaving the door open for an extension of cuts that started in January. “The crude market is losing patience,” Mike Wittner, head of commodities research at Societe Generale SA in New York, said by telephone. “The big rally in December after the OPEC agreement was based on expectations that the cuts would balance the market. While it looks like OPEC has cut more than 1 million barrels a day of output it’s difficult to see any impact on U.S. stockpiles.” West Texas Intermediate for April delivery dropped $2.86, […]