Every year, companies form thousands of alliances (Kang and Sakai 2000; Cools and Roos 2005). During the first two years of the twenty-first century, more than 20,000 alliances were formed worldwide, compared with 15,000 mergers or acquisitions, according to a study by Harbison et al. (2000). However, between 1993 and 2008, more mergers and acquisitions occurred than alliances, and the difference in number appears to have widened since the mid-1990s, according to Thomson Financial data (Cools and Roos 2005). This apparent contradiction in the quantitative data is unsurprising, in part because strategic alliances remain less visible, and therefore probably underestimated, compared with more visible mergers and acquisitions. Also, the definition of ‘alliance’ varies between studies; for example, some only look at international alliances – more numerous than national ones, according to available censuses. If national alliances are included with international ones, their share compared to that of international mergers and acquisitions increases to more than 50 percent in some years (Kang and Sakai 2000).