Greencore shares fell 9.5% in London after British supermarket chain Asda withdrew its beef bolognese sauce due to the possible presence of horse DNA.
Greencore said it was waiting for test results to quantify how much DNA was in the sauce.
It said the meat used was supplied by ABP Foods in Co Tipperary.
Merrion says this will serve as a frustration for Greencore management.
In a statement this morning Greencore said it also withdrew three other Greencore products, none of which contain equine DNA, as a precautionary measure - 600g Beef Broth Soup, 500g Meat Feast Pasta Sauce, and 400g Chilli Con Carne Soup.
It said the revenue of the Beef Bolognese Sauce represented about £0.3m of Greencore's £1.16 billion turnover in its last financial year.
The annualised revenue of all products withdrawn represents less than £1m.
It is waiting for the results of further quantitative tests on the 350g Beef Bolognaise Sauce that will validate the presence and the extent of the equine DNA.
The statement said: "Greencore is committed to maintaining the highest standards of food safety and food traceability, and is therefore extremely concerned that the quality of one of its products may have been compromised in this way."
It added: "The company is participating in full with the intensive industry testing programme to examine the full supply chain in order to restore consumer confidence."
Separately, ABP confirmed it is a supplier to Greencore but said it never knowingly bought or processed horse meat.
ABP also said that in the last few weeks the company has carried out hundreds of tests on fresh beef and to date they have all tested negative for equine DNA.
Stockbroker Merrion, in a note this morning, says that the product removal by Asda comes at a difficult time for UK food retailers as they continue to try and trace all equine DNA.