Clifford Chance (CC), Skadden Arps Slate Meagher & Flom and DLA Piper are among a number of law firms to have advised on the initial public offering (IPO) of Pfizer's former animal health business Zoetis, in the largest IPO by a US company since Facebook.

The listing, which went ahead on the New York Stock Exchange at the start of February, is said to have raised $2.2bn (£1.4bn), valuing the company at around $13bn (£8.3bn). Pfizer will retain an 80% ownership of Zoetis.

Zoetis has revenues of $4.2bn (£2.7bn) and 9,000 employees worldwide. With the IPO, Pfizer has created the world's largest standalone company fully devoted to animal health medicines and vaccines.

Owing to the vast geographical spread of its operations, legal roles were split between Pfizer's main advisers. CC, which fielded a team led by Duesseldorff partner Christoph Holstein, advised on pre-IPO restructuring and due diligence in Asian and European jurisdictions, consulting external advisers in countries where the firm had no office.

The core team at CC also comprised corporate associate Hi-Zin Pak, counsel Daryl Fairbairn, senior associate Trevor Wedman and associates Philipp Heer and Dominik Kruse.

Holstein said the role – which involved the creation of standalone entities in each of the relevant jurisdictions which were then brought under the parent company – took 18 months.

CC's international team also involved lawyers in Amsterdam, Bucharest, Hong Kong, Istanbul, London, Madrid, Moscow, Paris, Prague, Shanghai and Warsaw.

Elsewhere, Skadden advised Pfizer on the carve-out of Zoetis, due diligence in the US, and a $3.65bn (£2.34bn) offering of Zoetis senior notes, which closed in January. DLA Piper also advised on the restructuring, as well as due diligence in several jurisdictions including the Africa, the Middle East and Latin America.

Skadden's New York  team included corporate finance partners Stacy Kanter and Dwight Yoo, tax partners Dean Shulman and Steven Matays, and M&A partners Paul Schnell and Thomas Greenberg.

A large number of banks took roles on the listing, with JP Morgan, Bank of America Merrill Lynch and Morgan Stanley serving as joint lead book-running managers.

Facebook's multibillion-dollar IPO last year saw US law firms Fenwick & West and Simpson Thacher & Bartlett secure the lead roles, advising the social media giant and the underwriting banks respectively.