William Hill CFO Ruth Prior has resigned to join Elemental Materials Technology in the same role.
Prior however, has a 12-month notice period and her departure date will be determined "in due course."
Joining the company in October 2017, Prior drew gratitude for the professionalism she had shown since Ulrik Bengtsson's appointment as William Hill CEO.
Prior said: "I have enjoyed my time at William Hill and believe the company is in a strong position to take advantage of many opportunities ahead and deliver improved business and financial performance. I wish the business every success in the future”.
Meanwhile, the organisation provided a positive trading update roughly a month ahead of its scheduled full-year results release.
William Hill’s full-year adjusted operating profit for 2019 is expected to be in the range of £143m ($185.4m) to £148m.
This is ahead of "market and management expectations" and was driven "by favourable sporting results."
However, this total would still only be just over half the adjusted operated profit generated for 2018.
Bengtsson said: "The group has delivered a strong operating performance, ahead of our expectations and against a challenging regulatory backdrop.
"We made good progress on a number of fronts, including our retail business, online and in the US, enabling us to deliver on our long-term strategic ambitions."
William Hill's share price rose from £1.84 to £1.94 during the morning of its trading update; it has since lowered to around £1.86.