Updated from 3:12 p.m. EST

Bank of America ( BAC) CEO Ken Lewis on Thursday faced a call for his ouster from a large institutional investor, who blamed "outsized, reckless risks" for severely undermining confidence in the company.

CtW Investment Group, which represents pension funds and affiliates with nearly $2 trillion in assets under management, sent a letter to lead director O. Temple Sloan, calling on the board to remove Lewis. CtW plans to campaign with other shareholders to vote against the re-election of Lewis, Sloan and Thomas Ryan, chair of the corporate governance committee, at an upcoming annual meeting.

CtW is an activist group that often pushes for leadership and operational changes, with the goal of increasing stock returns for the six million union members it represents. CtW funds and affiliated Taft-Hartley plans hold 116 million shares of Bank of America, whose market value has plunged over 90% over the past year.

Using those figures and closing share prices, the CtW investment was worth $4.36 billion last year, but just $416.4 million at Wednesday's close.

"I was just looking at a stock chart and the failure has been staggering," says William Atwood, executive director of the Illinois State Board of Investments. "When BofA and the banks were all doing well, the executives were very well compensated because of their leadership. Now BofA has lost a huge percentage of its value, and you have to hold them accountable for this historic failure."

Atwood oversees retirement funds for the state employees, judges and the general assembly, which include 1.6 million BofA shares. Those holdings have plummeted from $60.1 million to $5.7 million.

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