Pressure from institutional investors is building on Bank of America’s board to name an outsider to replace Ken Lewis, who retires as chief executive at year end. Three institutional investors are said to have urged BofA to consider external candidates, while another institution, Northern Trust, plans to raise concerns. Two insiders – retail banking chief Brian Moynihan and chief risk officer Greg Curl – are seen as top candidates among BofA executives although some board members have suggested two former BofA CFOs, Jim Hance and Al de Molina.