It's been a fast ascent for Barbara Desoer, who just joined Citibank as its chief operating officer in October 2013 and moved up to the CEO role in April. She now reports directly to Citigroup CEO Michael Group. One of her responsibilities is overseeing corporate governance of the bank in more than 100 countries, and she is busy making improvements on that front. Among her achievements to date are establishing the framework for new lending limits and strengthening corporate oversight of the bank's subsidiaries, geographies and business lines. Desoer, who previously spent 34 years at Bank of America, is among Citi's highest-ranking females and takes seriously her obligation to mentor other women. She is co-chair of Citi Women, an initiative devoted to grooming and retaining top female talent. Since joining the company, she has also personally mentored and advised more than 15 women who have reached out to her.