Ms. Edkins ended up at BlackRock in 2009, and later moved to San Francisco to lead its governance group. The way things worked in the United States, she said, came as a bit of a shock. Countries like Britain, she said, have a longer history of shareholders engaged in governance. “There is an agreed standard that has typically been developed by some commission,” she said. “Here, there is no uniform code.”

She said shareholders typically had more rights in Europe, which encourages companies to talk to shareholder groups. “In Europe it is about engagement,” she said. “Here it was, and still often is, about voting.” This, she said, leads to a more confrontational governance system in the United States.

She raised this issue at a June 2011 meeting of top BlackRock managers, including Mr. Fink. “Companies wait until the 11th hour to come to us or they assume we are going to follow I.S.S.,” Ms. Edkins says she told the group, referring to Institutional Shareholder Services, the shareholder advisory firm that recommends how shareholders should vote. “It’s frustrating.”

Mr. Fink was receptive to Ms. Edkins’s appeal. After the meeting, he wrote a letter to virtually every United States company in which BlackRock owns a stake. “Companies that focus only on gaining the support of proxy advisory firms risk forgoing valuable and necessary engagements directly with shareholders,” he wrote. “We reach our voting decisions independently of proxy advisory firms on the basis of guidelines that reflect our perspective as a fiduciary investor with responsibilities to protect the economic interests of our clients.”

The letter counted as very big news in the decorous world of corporate governance, and seemed to suggest that shareholder advisory firms, as non-shareholders, had too much influence on voting. The letter was also seen as a public declaration that companies should call BlackRock if they have a problem, and not assume that it would follow advisory firm guidance.

Just days after Mr. Fink’s letter was released, Martin Lipton and David Karp, Wall Street lawyers at Wachtell, Lipton, Rosen & Katz, wrote to their clients that “it is a helpful sign that a major institutional investor is willing to take a direct and pragmatic role in governance issues rather than outsourcing this responsibility to a proxy advisory firm or agitating for short-term results.”

MS. EDKINS oversees 20 or so people covering thousands of companies around the world, and BlackRock says they make their own decisions — regardless of the views of the firm’s portfolio managers or even Mr. Fink. During the 2012 proxy season, BlackRock voted shares on 129,814 proposals at 14,872 shareholder meetings worldwide. Almost 3,800 of those meetings were in the United States.

BlackRock analysts don’t comb through every shareholder proposal. Rather, Ms. Edkins says, the firm uses the advisory services I.S.S. and Glass, Lewis & Company to help summarize proxy statements. Once those services have identified an issue, BlackRock assigns an analyst to it.

J. Boyd Douglas, the president of CPSI, a health care provider in Mobile, Ala., said he was surprised when BlackRock withheld its vote for one of his company’s independent directors, W. Austin Mulherin, in 2012. Mr. Mulherin is a local lawyer and his firm, according to regulatory filings, annually receives “less than $120,0000” in legal fees from CPSI. This relationship called into question his independence (and earned the disapproval of I.S.S.).