Delaware Judge Leo Strine has ruled that Martin Marietta violated a nondisclosure agreement with Vulcan and used confidential information in forming its USD5.3bn bid and proxy fight. It has been ordered to suspend all activities related to the deal for four months.

Martin Marietta said on Monday, it would appeal the ruling: “We are disappointed with the decision rendered by the Delaware Court of Chancery, with which we strongly disagree,” the company said in a statement. “After carefully considering our options, Martin Marietta has determined to pursue an appeal and to seek a stay of the court’ ruling pending the outcome of the appeal.”

Martin Marietta made an unsolicited, all-stock bid for Vulcan in December, saying that creating the world's largest producer of sand, gravel and other building materials would provide up to USD250m in cost savings to investors.