THE ISEQ ended the week in the red after falling for three consecutive days.
By the close in Dublin, the Overall Index had fallen 0.65pc or 27.37 points to end the trading week at 4209.41.
The market closed down for four days this week, and ended lower than it did last Friday.
By contrast, European stocks rose – extending a second weekly gain for the Stoxx Europe 600 Index.
Aer Lingus led the laggards in Dublin, after the airline issued a profit warning following its failure to recoup passenger numbers that declined during the summer's heatwave.
The airline closed down 6.7pc to end the day at €1.48.
Aer Lingus also said it was examining ways of accelerating ongoing cost reductions and said that a voluntary redundancy scheme had been slowed due to an ongoing unresolved pension issue.
The airline, headed by chief executive Christoph Mueller, said that Aer Lingus was now likely to make a pre-exceptional operating profit of about €60m this year – less than the €69.1m that had been anticipated.
Specialty baker Aryzta was down 2pc to €47.89, while insulation company Kingspan dropped 1.7pc to €11.65.
On the other side of the board, drug company Elan increased 0.1pc to €11.52, while building materials company CRH fell 0.2pc to €17.52.
European stocks advanced, with the Stoxx 600 rising 0.2pc to 311.46 at the close in London after earlier dropping as much as 0.4pc.
National benchmark indexes climbed in 11 of the 18 western European markets.
France's CAC 40 and Germany's DAX each rose 0.2pc.
The UK's FTSE 100 fell 0.1pc.
"With acceptable macro data and some progress on the Syria issue, sentiment seems to have slightly improved," said Anja Hochberg, the chief investment officer for Europe and Switzerland at Credit Suisse Group in Zurich.
"In spite of our optimistic medium- to longer-term outlook, we stay on the sidelines for the time being.
"Markets are eagerly awaiting the Fed meeting next week."
German medical equipment company Fresenius rose 3.6pc after its Helios subsidiary agreed to buy 43 hospitals from Rhoen-Klinikum AG.