With oil and gas prices expected to be weighed down by fears of weakening demand as global economies slow, Mizuho analyst Nitin Kumar has downgraded the shares of a number of energy companies on Wednesday.Included in the ratings changes, Kumar cut his ratings on the stocks of Exxon Mobil Corp. XOM, +2.38% and Occidental Petroleum Corp. OXY, +0.57% to neutral from buy. He lowered is stock price targets for Exxon Mobil to $117 from $133 and for Occidental to $63 from $72.“Although OPEC+ continues to be suppor ...