A seven-partner Freshfields team, led by Barcelona corporate partner Antoni Valverde, advised La Caixa, with Linklaters and Davis Polk acting for underwriters UBS, Morgan Stanley and La Caixa's investment banking arm.
Miguel Loran, the Freshfields tax partner who worked on the deal, said: "It's been a huge amount of work. It's a recognition of our Barcelona - and whole Spanish - operation."
La Caixa is the main savings bank for Barcelona and Catalonia. The bank raised eyebrows in the legal market when it chose Freshfields over Catalan giant Cuatrecasas for the deal.
Loran said: "There were advantages in having a single firm as there was the possibility of working on both domestic and international work. The huge corporate, tax and capital markets departments at the firm made it much easier to get the job."
The Freshfields team included corporate partners Armando Albarrán in Madrid, Monica McConville and Don Guiney in London, Hong Kong partner Stuart Grider and Washington tax partner Gregory May.
The IPO makes Criteria CaixaCorp Spain's eighth-largest publicly listed company, owning stakes in national champions such as Repsol and Telefonica.