Reuters reports that Zynga has made four recent acquisitions, all mobile developers. Perhaps the most notable is its September purchase of San Francisco-based Page44, which ported World of Goo to iOS; the port has sold over 1 million copies. In August, Zynga got hold of fellow San Franciscans HipLogic, and New York team Astro Ape. Further afield, a December deal netted the German Gamedoctors in December. Zynga went public in December with the largest tech IPO since Google, but has suffered fluctuating stock price in the interim.