Whether or not President-elect Donald Trump will become a dealmaker or a divider in the White House remains to be seen, but the man who once wrote a book called “The Art of the Deal” could emerge as a so-called deal slayer.

Reuters Breakingviews reported Friday that while on the campaign trail, Trump was a vocal opponent of AT&T Inc.’s proposed $85.4 billion acquisition of Time Warner Inc. And while Trump has talked about getting rid of regulations ushered in by the Dodd-Frank Act, he’s also said he will reintroduce the Glass-Steagall Act, which kept commercial and investment banks apart until its repeal in 1999.