Willi Thurnherr, head of retirement at Mercer in Switzerland, will be leaving the consultancy on 30 September.
He had been in this position since 2007 and is rumoured to be joining another international consultancy in Zurich.
Catherine Schoendorff, chief executive at Mercer Switzerland, is to head the retirement business on an interim basis.
She confirmed to IPE that the consultancy was “looking into internal and external options” to replace Thurnherr.
“We are sure we will be able to present a successor shortly,” she added.
Further, Schoendorff stressed that Switzerland would remain a “market of great importance and a major growth opportunity” for Mercer.
Schoendorff herself had been named country head of Mercer Switzerland in January this year.
She joined the consultancy in 2011 after a decade at Hewitt as leader of its pension administration business in Belgium, the Netherlands, Germany and Switzerland.
Over the last year, there have been several shifts in the Swiss international consultancy universe, with former Publica head Werner Hertzog having left Aon Hewitt Switzerland in May 2014.
Around the same time, Edouard Stucki left as a senior consultant at Towers Watson Switzerland.
At beginning of 2015, he joined comPlan’s asset management team, managing the assets of Swisscom’s Pensionskasse.
In July last year, Mercer Switzerland announced its head of investment Christian Bodmer was to leave the consultancy.