The company also warned on earnings guidance, saying the cost of restructuring its agri business and looking for a new chief executive will mean earnings before interest, tax, depreciation and amortisation will be at the lower end of its previous guidance of $22.5 million-to-$26.5 million.
Bennett said he had led the company through a period of intense change which was largely through and that the time was right for someone else to take over the reins.
NZX's board will start an international search for a new chief executive, with the successful applicant needing a "strong priority" to grow shareholder value while at the same time, growing New Zealand's capital markets, Miller said.
Bennett's CEO share scheme will continue to run until August next year.
NZX shares last traded at $1.05 and have dipped 1.9 per cent this year. The stock is rated an average 'hold' based on three analyst recommendations compiled by Reuters with a median target price of $1.11.