By Colin Kellaher 



  United Parcel Service Inc. on Monday said Pfizer Inc. executive Angela Hwang has joined its board, expanding it to 13 directors and boosting female representation to 31%. 


  Ms. Hwang is group president of Pfizer's biopharmaceuticals group, which accounts for roughly 80% of the New York drugmaker's revenue, and a member of Pfizer's executive team. 


  The Atlanta package-delivery giant said the addition of Ms. Hwang, who is joining the board's audit committee, complements its efforts to expand in the healthcare logistics sector. 


  With Ms. Hwang's appointment, women now hold four of UPS's 13 board seats. Many gender diversity advocacy groups aim to reach a near-term target of 30% female representation on public company boards. 


  Carol Tome, a director since 2003, in June became the first woman to serve as CEO of UPS in company's 113-year history and the first outsider to hold the top job. 


  Ms. Hwang also becomes the first current UPS board member of Asian descent and, at 54 years old, its second-youngest director. 


  Write to Colin Kellaher at colin.kellaher@wsj.com