Pfizer announced on Sunday that CEO Jeff Kindler has retired from the company, and that Ian Read, Pfizer’s head of biopharmaceutical operations, will step into the role as president, CEO and director.

Kindler, who served in the top executive position for a little over four years, and who oversaw Pfizer’s acquisition of Wyeth, said in a statement that his retirement will provide an “opportunity to recharge my batteries, spend some rare time with my family and prepare for the next challenge in my career.” Kindler’s successor, Ian Read, touted Pfizer’s “broad portfolio that spans the entire spectrum of human and animal health, from vaccines to biologics to primary care, specialty care, oncology, consumer products, nutritionals and beyond,” in the statement.

Read joined Pfizer in 1978 as an operational auditor, and was appointed president of the company’s international pharmaceuticals group in 1996. He became EVP, Europe, in 2000, and corporate vice president in 2001. Read serves on the board of Kimberly-Clark, as well as on the US Council for International Business and the European Federation of Pharmaceutical Industries and Associations, according to his Pfizer bio.

In a note to investors, Deutsche Bank’s Barbara Ryan said that Kindler “was successful, in our opinion, in digging Pfizer out of a substantial hole,” by cutting sales forces and creating a leaner organization. With respect to the Wyeth acquisition, Ryan wrote that Kindler “diversified the revenue base into high value, long tail assets, and diluted the dependence on Lipitor,” Pfizer’s best-selling product, which faces patent expiry in the US next year.

Ray Kerins, a Pfizer spokesperson, told Bloomberg that Kindler “wasn’t pushed out,” but declined to comment further. Pfizer did not immediately respond to a request for comment.

PhRMA, the industry trade group, named Kindler – who once served as law clerk to former US Supreme Court Justice William J. Brennan, Jr. – as its board chairman in March, a position that typically lasts one year. In a statement today, PhRMA announced that Chris Viehbacher, CEO of Sanofi-Aventis, would assume the role, replacing Kindler as a result of his resignation from Pfizer. In the statement, PhRMA said of Kindler: “Jeff helped navigate us through the passage and implementation of healthcare reform, in the process strengthening Medicare Part D and expanding coverage to millions of Americans in need.”