Ann-Marie Costello
Dublin, City Quay
Partner - Deal Advisory

Ann-Marie Costello


Ann-Marie joined Grant Thornton's Advisory Practice in 2012, having trained in a Big Four firm. Her area of expertise is predominantly Lead Advisory, acting both buy-side and sell-side on deals, as well as Transaction Advisory Services and Debt Advisory Services.  

Ann-Marie was the Chairperson of Chartered Accountants Ireland Leinster Society for the 2022-2023 term and is also involved in Grant Thornton’s Diversity, Equity and Inclusion platform.

Sector experience

Ann-Marie’s has extensive experience advising clients, both in Ireland and internationally, across a wide variety of sectors. She has provided advice to clients on both sell-side and buy-side mandates, financial due diligence, valuations, debt restructures and fundraisings across areas such as healthcare and pharmaceuticals, TMT, industrial manufacturing, food and agriculture and hospitality.

Ann-Marie’s recent experience includes:

  • Lead advisory services to Acacia Facilities Management Limited on their sale to Apleona Group
  • Lead advisory services to Prodieco Limited, an international pharmaceutical engineering business, on their sale to Agilitas Private Equity
  • Lead advisory services to Ballytherm Limited, an large insulation business, on their sale to Unilin
  • Buy side advisory and diligence services to Culligan, a global private equity backed water treatment business on their Irish acquisitions
  • Buy side due diligence services to DIF Capital, on their acquisition of various Irish nursing homes
  • Financial advisory services to I-RES REIT
  • Sell side financial advisory services Writech Group on their sale to Waterland Private Equity
  • Lead advisory services to GEM Plastics on their sale to Schuetz
  • Buy side due diligence services to UFP Technologies on their acquisition of Advant Medical
  • Debt advisory services to a large Irish agriculture business on various refinancings
  • Valuation services to a number of Irish SMEs
  • Fellow of Chartered Accountants Ireland (CAI)
  • Masters of Accounting degree (MAcc) from Smurfit Business School, University College Dublin
  • Bachelor of Commerce (International) degree (with German) from National University of Ireland Galway
Ann-Marie Costello
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Partner - Deal Advisory
Ann-Marie Costello
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