Those corporations - which include Wells Fargo, UPS, Ford, Motorola, JPMorgan Chase, and Walgreens - have not explicitly said that the expected nomination of Donald Trump was a factor in their decisions, but each had been a sponsor for the 2012 convention in Tampa, Florida.
The Bloomberg report notes that many of the companies say that they won't back the Democratic convention either.
Large companies typically sponsor the conventions to help pump up their brands, even if they remain politically nonpartisan.
The corporations are joining a growing list of prominent Republican politicians and donors that have declared they'll sit out of the convention, including former Presidents George W. Bush and George H.W. Bush, Arizona Sen. John McCain, 2012 GOP presidential nominee Mitt Romney, and the Koch brothers, billionaire donors known for supporting conservative causes.
RNC national committeeman James Dicke told Bloomberg that he's not worried: "Fundraising has slowed down, but we will get there and, so far, we've raised considerably more money than any other convention has ever raised."