DLA Piper international senior partner and global co-chair Juan Picon has quit the firm to join US rival Latham & Watkins.

The move, a rare example of a law firm leader leaving for a competitor, will see Picon join Latham as Madrid office head after just 18 months at the helm of DLA.

Picon, a corporate partner and Spanish national, was appointed senior partner of DLA Piper International – which comprises the firm's operations outside of the US – in March 2016, taking over from longstanding leader Sir Nigel Knowles.

He is making the move to Latham's Madrid office alongside two DLA Madrid corporate partners – Spanish corporate head Jose Antonio Sanchez-Dafos and capital markets partner Ignacio Gomez-Sancha.

Latham managing partner Bill Voge said: "We are delighted to welcome Juan, Ignacio and Jose to the firm. We have a top-notch team in Spain, and the arrival of this group will be a perfect complement to our existing practice. The team's market knowledge and industry contacts are second to none. Spain is a key market with exciting opportunities in our global platform."

Picon has stepped down as senior partner and global co-chair of DLA with immediate effect, but has not yet agreed a date to leave, and remains a partner at the firm for now. His role will be filled in the interim by disputes partner Janet Legrand, the firm's senior elected board member. An election will be held to determine Picon's replacement in due course.

He will take over the role of Madrid managing partner at Latham from Jose Luis Blanco, who is retiring from the firm. Blanco is a founding partner of Latham's Spanish practice and has served as Madrid managing partner since joining from Cuatrecasas to lead the US firm's launch in the country in 2007.

Picon started his career at Santander in Madrid, before joining Clifford Chance as an associate. Between 1997 and 2006 he was a partner at legacy Squire Sanders & Dempsey, before moving to DLA in 2006. He was made Europe, Middle East and Africa head of corporate in 2007, and appointed managing director of groups and services in 2012.

As global co-CEO he worked in tandem with Simon Levine, who succeeded Knowles as co-CEO in January 2015.

Levine said: "We are disappointed that Juan has decided to leave before completing his term as senior partner but we recognise the unique personal circumstances that have led him to make this decision. We wish Juan all the best for the future."

Knowles recently joined DWF as chairman after leading DLA Piper for two decades. He stepped down as global co-chair and senior partner of DLA's international partnership at the end of April 2016, and retired as a partner in June that year.

Picon's move, and that of Knowles, are extremely rare examples of management moves between the top echelons of the legal market.

A number of the few recent examples have DLA as a common thread. In 2011, former Linklaters managing partner Tony Angel joined the firm as global co-chair and senior partner.

In the US, DLA is led by global co-chair Roger Meltzer and global co-CEO Jay Rains, who have held their roles since January 2015.