Big changes atop Bank of America’s investment banking division after a shaky 2011 where the bank’s income dropped nearly $3 billion from the previous year, owing in large part to European debt woes. Bank of America has named 42-year-old Christian Meissner head of global investment banking, and two other top executives will assume new roles in the division. They will all answer to co-CEO Thomas Montag, who announced the changes to employees in a memo on Sunday. “The new structure is a natural evolution of our corporate and investment-banking model as we continue to adapt to a changing market environment,” Montag wrote.