Brown Brothers Harriman, the oldest US private commercial bank, has appointed partner Douglas "Digger" Donahue as its new managing partner to succeed Michael McConnell.

BBH focuses on wealth management and commercial banking for mid-size companies. The firm has 3,600 employees, and its investment management business oversees about $45 billion.

Mr Donahue, currently a BBH partner and global head of Investor Services, joined the firm in 1976 from Harvard Business School.

Mr McConnell, who became managing partner in 2002, is to remain a partner at the firm.