Deirdre Somers has resigned from her position as chief executive of Euronext Dublin, which owns the Irish stock exchange.
Euronext said it has nominated Daryl Byrne as her replacement.
Ms Somers had been CEO of the Irish Stock Exchange for the last ten years after joining it in 1995.
"After almost a year dedicated to building the best future for the company, I have decided to begin the next chapter of my business career," Ms Somers said in a statement.
"I am leaving, confident that the integration of the Irish Stock Exchange within Euronext offers the best opportunities for all our clients and stakeholders.
"Daryl Byrne is the best leader to complete the integration and pursue the implementation of Euronext's ambitions for Euronext Dublin," she added.
Mr Byrne joined the Irish Stock Exchange in 2000 and has held a number of senior management roles since then including chief regulatory officer.