The ISEQ index closed down 7.55 points to 2,926.45, a drop of 0.26%.
Top faller was Merrion Pharmaceuticals, which closed down 33c or 19.08% to €1.40.
Also in the red were Tullow Oil, down 60c to €15.05; DCC, down 40c to €20.60; CRH, 14c off at €14.85, and Kingspan, with a loss of 8c to close at €7.02.
On the risers' board, Elan Corp gained 13c to €6.31, Providence Resources was up 10c to €3.00 and FBD added 5c to €7.30.