short answer: yes.
there are two ways to rule a nation: first is to rule directly and openly, tell the people what to do, write laws, etc. another (less obvious) way is to leave it to a loyal puppet while only stepping in when absolutely necessary. today's corporations rule the second way.
corporations really don't "fight" one another because they only care about their market share. it's hard to image a soda company fighting an energy company. a soda company will compete with a competitor in the same market but will then cooperate with that same competitor via a lobbying group to get what they want from the gov.
every industry has its lobbyists who write the laws and tell the politicians to vote for them. the lobbyists promise money and reelection and they deliver. it's a well-oiled and perfectly legal system.
the problem is that short term profits sometimes lead to long term problems. everyone has diabetes. nobody knows what a carrot looks like. can big pharma save us all?
don't like it? vote for another party. also vote with your wallet, buying from smaller, local companies. good luck!