The full extent of the row was only laid bare when it emerged this year that Mr Pitt had used whistleblowing legislation to complain as a dispute inside the media firm raged over the potential acquisition of broadcaster Newstalk.
Market sources said details of the terms of a financial settlement will be eagerly awaited.
Mr Pitt was paid a basic salary of €404,000. That payment rises to €566,000 when an annual incentive, a pension payment, and allowances are included.
INM disclosed earlier this year that the Office of the Director of Corporate Enforcement — the ODCE — had asked it for documents involving plans it had to acquire Newstalk.
The controversy arose in late 2016 between Mr Pitt and chairman Leslie Buckley about the value of a potential acquisition of Newstalk. At the time, INM had referred to “an issue” between its CEO and chairman but did not identify the potential acquisition. INM had said that Mr Pitt had raised the issue with the company’s senior independent director.
Denis O’Brien is a significant shareholder in INM and founder of Communicorp, which owns Newstalk. The news that the chief executive used whistleblowing legislation raised the heat over the controversy and showed the seriousness of the row.
In a short statement yesterday, INM said that Mr Pitt “has decided to leave the business with effect from Friday 13 October 2017, to pursue other interests”.
At a tense shareholders’ meeting in August, INM confirmed that the ODCE had asked the company “to produce records in relation to the possible acquisition by the company of Newstalk and related matters”.
Mr Pitt, who had sat with Mr Buckley, abstained from the vote to re-elect Mr Buckley as chairman. Mr Buckley was re-elected by a majority of shareholders.
The company in August said: “A requirement from the ODCE to produce books and records is a procedural matter that does not involve any conclusion that there has been a breach of law by the company or its officers.” The company holds almost €90m in cash.
Philip O’Sullivan, chief economist at Investec Ireland, said Mr Pitt had done a good job in the last three years in turning around the media company’s balance sheet. But his departure did “not come as a surprise given the issues” involved, Mr O’Sullivan said.