Shares in Kingspan fell sharply today marking one of the steepest daily falls for the building products giant since it started giving evidence in early November to London's Grenfell Inquiry into the tower block fire that killed 72 people in 2017.
The shares slid 12% to €57.80, which an analyst said was possibly linked to the Grenfell Inquiry that earlier this week was suspended for a month.
More than €3.5bn has been shaved from Kingspan's stock market value since early last month. The company makes insulated panels and boards for world markets and some of that product, Kooltherm K15, were used in the refurbishment of the Grenfell tower block. Most of the insulation came from another firm, Celotex.
In a website posting on Wednesday, the firm said it condemned "any actions that do not demonstrate a proper commitment to fire safety".
"The inquiry has highlighted historic process shortcomings and unacceptable conduct within a part of our UK Insulation business, for which we have apologised unreservedly and which we are treating with the utmost seriousness," it said.
Last week, the Grenfell Inquiry heard that Kingspan worked with a public relations agency to lobby MPs weeks after the blaze.
Kingspan used Portland over the summer of 2017 to try to convince "key decision-makers" that combustible materials were safe if properly installed. It had listed ideal targets on internal documents including then-home secretary Amber Rudd, and then housing secretary Sajid Javid, who went on to be chancellor under Boris Johnson.
Michael Gove, who still serves in the British cabinet, was also noted as a "key decision maker" as the secretary of state for environment, food and rural affairs at the time. The inquiry also heard that Kingspan had issues obtaining a Class 0 "limited combustibility" rating for its K15 product, and only claimed it as such by partially testing the product.
Kingspan is due to give more evidence when the inquiry resumes in January.
It has weathered the Covid-19 crisis remarkably well. In the summer, chief executive Gene Murtagh unveiled net profits that had only fallen to €147.5m in the six months to the end of June, despite the Covid disruption.