The Iseq index had a lacklustre day, slipping 6 points as investors remained nervous about the strength of the Irish banks and a new US report showed that its economy lost more jobs than estimated in September.
Credit ratings agency Standard & Poor's cut its long-term rating on AIB to "BBB+" from "A-", bringing it three notches above junk status.
"In our opinion, the ability of AIB to return to an A category standalone credit profile is unlikely for a number of years," S&P said in a statement. AIB's share price fell to 39 cent, down 1 cent or almost 3 per cent.
Bank of Ireland also drifted back, closing down 4.2 per cent at 65 cent, while Irish Life & Permanent held steady at €1.55.
Exploration group Kenmare, which reported a leak in its mine in Mozambique, fell in trading on both the London market, where it has its primary listing, and in Dublin, where it weakened 12.7 per cent to 19 cent.
Building materials group CRH, the largest stock on the index, also had an uneventful day, finishing up 9 cent at €12.49.
Drinks group C&C was also flat, closing at €3.03 ahead of the release of its interim results next Tuesday. Analysts expect the performance of its Magners and Tennent's/ABI brands to compensate for weaker returns in Irish cider. Magners volumes are up 4 per cent in the first half, according to Nielsen data.
There was little action among the airlines, as Ryanair climbed 1 per cent to €4.11, while Aer Lingus was flat at €1.11.
It was a strong day for the pharmaceutical stocks, with Elan finishing up around 2.6 per cent at €4.18. This follows a proposal by the UK's National Institute for Clinical Excellence that Alzheimer's disease treatments should be extended to a wider group of patients.
