A pension fund that holds shares in NYSE-Euronext has sued the exchange operator over its proposed $8.2 billion sale to IntercontinentalExchange, saying the deal undervalues the company's stock.

The New Jersey Carpenters Pension Fund on Friday filed a complaint in New York State Supreme Court in Manhattan contending that NYSE-Euronext breached its duty to maximize returns for shareholders. The lawsuit seeks class-action status on behalf of other NYSE-Euronext shareholders and aims to block the sale.