Cider sales have been struggling recently
Shares in Magners maker C&C have fallen more than 16% after it admitted having issued incorrect revenue figures.
Last week, the Dublin-based firm said revenues in the four months to 30 June had risen 3%, but it now says revenues actually fell by 5%.
However, C&C said its profit forecast remained unchanged.
Operating profit in the current year is expected to come in at the top end of its predicted range of 77m-82m euros ($107m-$114m; £67m-£71m).
"Today's update will put a question mark over management's credibility as they continue to try and re-establish the Bulmers and Magners brands," said NCB Stockbrokers.
The company is still intending to spend up to 8m euros to promote its brands following recent good weather.
C&C group reported an operating loss of 59.2m euros for the year to February. The firm has been hit by the economic downturn and the continuing trend for people to drink at home.