Updated from 2:43 p.m. EDTCitigroup ( C) shares skyrocketed more than 50% Monday, after it named -- as expected -- four new independent members to its board of directors, including two former bank CEOs. Citi's new board members include Jerry Grundhofer, former chairman and CEO of US Bancorp ( USB), Michael O'Neill, the former chairman and CEO of Bank of Hawaii ( BOH) , William Thompson, the retired CEO of Pimco and Anthony Santomero, who was most recently a senior advisor at McKinsey & Co. and a former president of the Federal Reserve Bank of Philadelphia. Published reports on Friday had identified the four executives. Shares surged as high as $2.68, but closed up 30.9% to $2.33 on Monday. "This is a solid slate of candidates with extensive banking and financial services experience, a deep understanding of international credit and equity markets, and first-hand knowledge of the governing regulatory system," Citi's chairman Richard Parsons said in a statement. "These outstanding individuals will be great stewards for Citi as it navigates the ongoing challenges in the present environment and works to restore profitability," Parsons added. "As I said earlier this year, we are committed to reconstituting the board with a majority of new independent directors. The election of these candidates will be a major step toward achieving our goal." Citi has received a total of $45 billion along with the backing of some $300 billion in assets from the U.S. Treasury. The company recently reached an agreement with the government for it to convert a portion of its preferred stake into common shares. The change will allow Citi to build its tangible common equity ratio, which has increasingly been scrutinized by investors and analysts as a measure of banks' capital levels.