The latest Bristol-Myers-Celgene twist is upon us

As Bristol-Myers Squibb defends its $74 billion plot to merge with Celgene through cunning use of PowerPoint, a pair of superlatively influential shoes are about to drop.

ISS and Glass Lewis, a pair of shareholder advisory firms, are days away from issuing their opinions on whether the deal is a good idea. Combined, the two companies hold about 97 percent of the market for investor advice, and their opinions on proposed mergers have historically swayed shareholder votes.

A negative recommendation would be bad for Bristol-Myers, but it wouldn’t necessarily doom the Celgene deal. In 2016, Glass Lewis recommended shareholders vote against Tesla’s bid to buy Solar City, and then the measure passed with 85 percent of the vote. And ISS and Glass Lewis have repeatedly advocated for ballot measures that would change things at Facebook, all to no avail.