Who is Bill Ackman, the hedge-fund billionaire who used corporate-raider tactics to push out Harvard’s president?

Bill Ackman has spent much of his career investing in undervalued companies, demanding change and pursuing very public pressure campaigns — often moving to oust the management or the board. - Matthew Eisman/Getty ImagesBill Ackman’s calls for the removal of Harvard University President Claudine Gay were ripped straight out of a corporate raider’s playbook.Most Read from MarketWatchIt was a natural approach for the billionaire hedge-fund manager who made his name as an aggressive activist..