Railways Pension Trustee Company chief executive Phil Willcock has quit the scheme after only 10 months to take up a position as head of AIG UK Life.
The Railways Pension Trustee Company - which runs the railway pension schemes through its subsidiaries RPMI and RPMI Railpen - said the process of appointing a new chief executive would now begin, supported by RPMI chairman Babloo Ramamurthy.
Willcock had begun work at RPMI at the begining of this year - joining from Aviva, where he had been, most recently, chief executive of Aviva Italy.
Commentating on Willcock's departure, Ramamurthy said: "We will be seeking to recruit a high calibre successor who will help deliver RPMI's mission of paying members' pensions securely, affordably and sustainably and provide support to the trustee of the Railways Pension Scheme."
Pension Protection Fund (PPF) chief financial officer Andy McKinnon is stepping down from his role after seven years.
Aon has announced the promotion of seven of its UK retirement, asset management and reward team to partner.
Long-serving Aegon UK chief executive (CEO) Adrian Grace will be replaced by Mike Holliday-Williams on 1 October.
Amber Rudd has resigned as secretary of state for work and pensions with immediate effect, with Thérèse Coffey named as her successor.