Before the close of trade, GNC regained some of its lost ground to trade at $5.97 for a percentage loss of 2.77%, after slumping to a low of $5.81 (5.37%) this morning.

Yesterday, Graincorp closed at $6.14.

In a statement released to the ASX today, GrainCorp chairman Don Taylor said the board thanked Mr Irwin for his contribution and wished him well for the future.

"Mr Irwin had driven significant change within GrainCorp since he became Managing Director in March 2008. He successfully led the acquisition in November 2009 of United Malt Holdings and introduced a range of internal reforms," Mr Taylor said.

On his resignation, Mr Irwin said he appreciated all the support from the board and employees during the move to a deregulated wheat market.

"Together with the balance sheet initiatives of mid 2009 and the United Malt Holdings acquisition in November 2009, we have transformed GrainCorp into an international agribusiness.”

Mr Irwin’s separation package comprises a cash component and a component of discretionary short term incentive payments and accelerated vesting of a proportion of retention and performance share rights, with an aggregate value of $750,000.

Chief financial officer Ian Wilton has been appointed as interim CEO while the board searches for a new managing director and CEO.

“Ian joined GrainCorp in June 2009 as the CFO and played a very important role in the recent acquisition of United Malt Holdings. He has extensive international and Australian agribusiness and grains industry experience and is the former CFO of ConAgra Malt, the company that subsequently became United Malt Holdings,” Mr Taylor said.

In announcing the appointment of Mr Wilton as interim CEO, Mr Taylor also reaffirmed GrainCorp’s earnings guidance provided to the market on 22 December 2009.