Ballmer says that he regretted the lack of focus on Windows Mobile in the early 2000s, leaving Microsoft a distant third in the current smartphone market. Moreover, he attributed the success of the expensively-priced iPhones to carrier subsidies. He went on to say, He called the acquisition of the mobile phone division of Nokia as his "toughest decision" during his tenure, as it was overseeing the changing profile of Microsoft as it was expanding on hardware. Ballmer hosted his last company meeting in September 2013, and stepped down from the company's board of directors, in August 2014. On December 24, 2014, the "Seattle Times" reported that the IRS sued Ballmer, Craig Mundie, Jeff Raikes, Jim Allchin, Orlando Ayala and David Guenther in an effort to compel them to testify in Microsoft's corporate tax audit. The IRS has been looking into how Microsoft and other companies deal with transfer pricing. Ballmer served as director of Accenture Ltd. and a general partner of Accenture SCA from 2001 to 2006. In 2007, Ballmer said "There's no chance that the [Apple] iPhone is going to get any significant market share. No chance." Speaking at a conference in NYC in 2009, Ballmer criticized Apple's pricing, saying, "Now I think the tide has turned back the other direction (against Apple). The economy is helpful. Paying an extra $500 for a computer in this environment—same piece of hardware—paying $500 more to get a logo on it? I think that's a more challenging proposition for the average person than it used to be." In 2015, Ballmer called Microsoft's decision to invest in Apple to save it from bankruptcy in 1997 as the "craziest thing we ever did". By 2015, Apple was the world's most valuable company. In 2016, Ballmer did an interview with Bloomberg where Ballmer added context to his iPhone statement, saying "People like to point to this quote...but the reason I said that was the price of $600-$700 was too high", he says he did not realize the business model innovation that Apple was going to deploy, using the carriers to subsidize the phones by building the cost into the customer's monthly bill. In July 2000, Ballmer called the free software Linux kernel "communism" and further claimed that it infringed with Microsoft's intellectual property. In June 2001 he called Linux a "cancer that attaches itself in an intellectual property sense to everything it touches". Ballmer used the notion of "viral" licensing terms to express his concern over the fact that the GNU General Public License (GPL) employed by such software requires that all derivative software be under the GPL or a compatible license.