Ambac Financial ( ABK) on Tuesday named veteran risk officer David Wallis to head the company as president and CEO. Wallace replaces Michael Callen, who was named interim president and CEO in January. Then-CEO Robert Genader retired as the company was about to report a $3.26 billion loss for the fourth quarter, slash its dividend and raise at least $1 billion in capital to maintain its top-notch rating. Callen will remain executive chairman of the board. Wallis, who has worked at Ambac for 12 years, most recently as chief risk officer, said his "immediate focus is to restore confidence in our balance sheet through aggressive risk reduction." He added that his "ultimate goal is to bring this company back to its position of leadership in the industry." Ambac shares were falling 1.8% to $3.34 in recent trading.