When Ken Lewis wasn't timing the Countrywide purchase just right or glowing from deftly outsmarting John Thain in the Merrill deal, he was apparently busy driving out more than half of the top 100 executives that made him 2008 Banker of the Year. When chief risk officer Amy Brinkley leaves this summer, she will be the 52nd departure of the top 100 executives who were at the bank in 2005. If you think that number sounds a bit high, you're probably right.

Many companies begin to worry if they lose 5 percent of their top executives per year, said Bradford Bell, an associate professor at Cornell University specializing in human resources issues. Other experts said annual turnover around 10 percent would be considered at the high end. Bank of America's turnover of top executives equates to 13 percent per year.

"For top talent, that is quite large," Bell said. "Companies devote a lot of resources to keeping these people happy and keeping them in the company."

But a BAC spokesman says there is absolutely nothing to worry about here. This kind of attrition is totally normal.

"The level of leadership turnover we've experienced is consistent with the history of the organization and a consolidating industry," said Bank of America spokesman Scott Silvestri.

Any leadership changes over the four years included "retirements, career changes, relocations and voluntary and involuntary departures," but he declined to comment on the specific numbers.

There is nothing that engenders confidence in an institution quite like a revolving door at the top.

Turnover in BofA's top ranks raises questions on stability [Charlotte Observer]