Following her forced resignation from HP, several commentators ranked Fiorina as one of the worst American (or tech) CEOs of all time. In 2008, "InfoWorld" grouped her with a list of products and ideas that flopped, declaring that her tenure as CEO of HP was the sixth worst tech flop of all time, and characterizing her as the "anti-Steve Jobs" for reversing the goodwill of "geeks" and alienating existing customers. During Fiorina's tenure as CEO, HP leased or purchased five planes, including two Gulfstream IVs, to replace four aging aircraft, only one of which had the range to fly overseas. One Gulfstream IV, acquired at a cost of 30 million and available for Fiorina's "exclusive" use, became a rallying point among HP employees who complained of Fiorina's expensive self-promotion and top-down managerial style during a time of company layoffs. Jeffrey Sonnenfeld of Yale School of Management said in August 2015 that problems with Fiorina's leadership style were what caused HP to lose half its value during her tenure.