By SUSANNE CRAIG, The New York Times

AT 11 a.m. on a Wednesday earlier this month, Michelle Edkins and her team began wheeling extra chairs into a cramped conference room in a San Francisco office tower, preparing for the corporate-governance equivalent of speed dating.

 Once settled, Yumi Narita started describing the disappointing qualities of a big entertainment company she’d been checking out. “I’m inclined not to trust this compensation committee,” she told the group.  “Year-over-year, they pay their C.E.O. more, and the metrics are often questionable.”

There were sympathetic nods around the room. Ms. Narita is one of about 20 analysts on the corporate governance team at BlackRock, the world’s largest asset manager. BlackRock’s size is mind-boggling. With almost $4 trillion under management, it is, according to a recent University of Michigan study, the single largest shareholder in one of every five United States companies. It manages money from pension funds and endowments as well as retail investors, controls large stakes in companies like JPMorgan Chase, Wal-Mart and Chevron and owns 5 percent or more of roughly 40 percent of all publicly traded companies in the country.

These investments give BlackRock tremendous influence, particularly now, during proxy season. At this time of year, public companies hold annual meetings, and shareholders vote on executive pay and elect corporate directors. Inside BlackRock, the small group of analysts led by Ms. Edkins meets every morning for about an hour, hashing out how BlackRock will vote its clients’ shares in hundreds of contests, zeroing in on directors they feel have been around too long, or ones who they think are overpaying executives.

These analysts have a language of their own, casually throwing around terms like “overboarding,” for when directors serve on multiple boards, possibly spreading themselves too thin; “engagement,” when a problem reaches a critical stage and merits a visit from a BlackRock analyst; and “refreshment,” when engagement doesn’t work and a director needs a heave-ho.

BlackRock is no activist investor. In fact, it’s far from it. It has never sponsored a shareholder proposal, and it rarely broadcasts its actions. Ms. Edkins says the firm generally votes against a director or a company proposal only when a behind-the-scenes “engagement” has failed.

A number of public pension funds and activist shareholders argue that BlackRock could use its influence to greater effect and say it sides with management far too often. It received a failing grade from the A.F.L.-C.I.O. in a 2012 survey; BlackRock voted with the federation just twice in 32 shareholder votes on issues that the union sees as important to the trustees of union pension funds.

 “We believe shareholders have the power and the obligation to use every tool at their disposal to encourage greater accountability,” said Brandon Rees, acting director of the A.F.L.-C.I.O. Office of Investment. “It’s disappointing that such a large company like BlackRock votes for so few shareholder resolutions.”