When Dominique Cerutti was appointed executive assistant to IBM’s legendary chief executive Louis Gerstner in 1998, the technology giant was staging a big comeback.

Five years earlier, it had been struggling to keep up with competition and its key mainframe computer business was bleeding millions. By shaking up the company's culture and refocusing its business, Gerstner brought the giant back to life in one of the most remarkable revivals in corporate history.