In an update, the mutual said the process to appoint a successor will now start and Ranger will continue to perform his responsibilities until at least the end of the year.
Ranger joined the firm in 2024, replacing Alasdair Lenman, who retired after seven years at Yorkshire Building Society.
He has over 25 years of experience in financial services and joined from Santander UK, where he held the role of group treasurer.
It is not yet known which firm Ranger will depart for.
A spokesperson for Yorkshire Building Society said: “Chief financial officer Tom Ranger has decided to pursue a new opportunity outside of the society.
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“The process to appoint a successor will now commence and Tom will remain with the society until at least the end of the year.”
Near the end of last year, Yorkshire Building Society appointed Tom Simpson as its managing director of homes and brought together its three separate mortgage businesses under a single ‘Homes’ division.
The firm also appointed Simon Watson as chief commercial officer in the past year.
