During Ballmer's 11-year reign as CEO, shares have declined more than 50 percent, even though sales have more than tripled and profit has risen 141 percent.
While investors' patience with Ballmer is wearing thin, Microsoft's board may not quickly agitate for change, said Pat Becker Jr., principal of Portland, Oregon-based Becker Capital Management, which holds Microsoft.
'Losing the Tech World'
"He doesn't have the investor base and my fear is he's losing his customer base and losing the tech world in general," said Becker, whose firm has about $2.5 billion in assets. "The investor base would welcome new leadership, but whether the board wants him to go is a different thing."
Ballmer's supporters could point to the company's sales and profit growth on his watch, said Michael Cusumano, a professor at the Massachusetts Institute of Technology's Sloan School of Management in Cambridge.
"Financially Microsoft has really done quite well," Cusumano said. "They are still printing money essentially."
Frank Shaw, a spokesman for Microsoft, declined to comment.
Other boards have shown less resistance to change. Hewlett- Packard directors pushed out former CEO Mark Hurd in August after an investigation found he violated the company's code of business ethics by concealing a personal relationship with a female contractor.
Hewlett-Packard, AMD, Google
Hurd's successor, Leo Apotheker, said this month that he inherited a company ill-equipped to win business from companies that want to switch to cloud computing. AMD board members ousted CEO Dirk Meyer in January amid frustration with the company's lack of progress in chips for tablets.
Google turned to one of its co-founders, Larry Page, 38, to succeed Eric Schmidt, 56, who ran the company for a decade. The move was aimed at helping Google bolster its defenses against Facebook and recapture the entrepreneurial ethos that fostered the creation of the most-used search engine.