Financial Markets Authority chief executive Samantha Barrass has resigned and will leave the regulator immediately, bringing her four-and-a-half-year tenure to an early end.

FMA chair James Miller says Barrass had previously advised the board she would not seek another term when her current appointment expires in January.

However, Barrass now needs to return to the UK after her elderly father was admitted to hospital. She will remain there to attend a governance course that was already scheduled.

“In those circumstances, the board has agreed with Samantha that she will leave her role now and that her suspension ends,” Miller says.

Alastair Hercus will become acting chief executive while the FMA board continues its search for a permanent replacement.

Barrass' departure follows several turbulent weeks in which she was suspended while allegations concerning her were investigated.

An independent investigation being undertaken by Paul Wicks KC will now be subsumed into an investigation commissioned by the Ministry of Business, Innovation and Employment (MBIE).

Barrass says she looks forward to participating in the MBIE investigation.

“The last few weeks have been very challenging for me, as I have found myself on the receiving end of allegations, and where I have had to take time out for them to be investigated,” she says.

“I won't comment further on them at this stage. That's for the MBIE investigation process to get to the bottom of, and I trust it will do so.”

Barrass says she feels privileged to have led the regulator and is proud of the changes made during her tenure.

“It has been a challenging mission reforming and expanding our regulator to become fit for its purpose and positioned for its next era. But it has been equally rewarding.”

During Barrass' tenure, the FMA's responsibilities expanded significantly, including greater oversight of banking and insurance, the transfer of consumer credit regulation to the authority and responsibility for climate reporting.

Miller thanked Barrass for her contribution and says farewell events will be held to recognise her time at the regulator.

Barrass also thanked Miller for his handling of the situation.

“I also want to personally thank James Miller, the incoming Chair, for his open-minded approach to this, and for supporting me to leave with grace and on good terms.”

She says she wishes Miller and the “new FMA” well.