BOSTON/LONDON (Reuters) - Billionaire investor William Ackman has decided to exit his large stake in Nomad Foods, selling out of one of his handful of investments at a time he is waging a proxy fight to push for change at another portfolio company.

William 'Bill' Ackman, CEO and Portfolio Manager of Pershing Square Capital Management, speaks during the Sohn Investment Conference in New York City, U.S., May 8, 2017. REUTERS/Brendan McDermid

Shares of Nomad, which makes Birds Eye fish fingers and Iglo vegetables, fell more than 4 percent on Wednesday after the company and Ackman’s Pershing Square Capital Management, the frozen foods company’s largest shareholder, said in a joint statement they were starting a public offering for the hedge fund’s stake of more than 33 million shares. The stake would be worth $497 million at Tuesday’s closing price of $14.92 a share.

They noted that the offering is subject to market conditions, and there can be no assurance as to its size or of whether or when it will be completed.

Ackman first invested in Nomad two years ago, through a so-called special purpose acquisition company. The investment in Nomad was a bright spot for Ackman’s Pershing Square, which is posting losses for the third consecutive year.

Nomad shares on Wednesday were down 4.2 percent to $14.29, still up sharply from the $10.50 Ackman paid in 2015. In the hedge fund’s interim financial report for the first six months of 2017, Ackman said it contributed 1.6 percent to the portfolio.

Nomad will purchase some of the shares Ackman is selling. The company said in a filing it plans to repurchase $100 million worth of shares.

A spokesman for Pershing Square declined to give any reason for Ackman’s decision to sell now. The move may have been hinted at several weeks ago when Brian Welch, a Pershing Square analyst, left the Nomad board to focus his attention on the hedge fund’s new big investment in Automatic Data Processing. Ackman is seeking to win three board seats at ADP and is pushing that company to eliminate inefficiencies.

Britain-based Nomad Foods was formed in 2014 as a vehicle to consolidate Europe’s slow-growth 25 billion euro frozen food market. Its anchor deal, Iglo, closed in June 2015 and the follow-on acquisition of Findus Group’s European business closed in November 2015.

Its chief executive told Reuters this year that the company was in a good position to do more deals.

After selling out of Nomad, the New York-based hedge fund will own nine long positions. It oversees $9.8 billion.

A spokeswoman for Nomad declined further comment beyond the joint statement.