Guillaume Isautier leads the Mergers & Acquisitions practice in France and is Deputy Head of the Paris Office.

He advises domestic and international clients in a wide variety of M&A transactions, including purchases and sales of listed and non-listed companies, strategic mergers and joint ventures, as well as business carve-out acquisitions and divestitures. His practice focuses on a broad range of industry sectors including banking, telecom, energy and consumer goods & retail sectors.  He also regularly represents private equity funds.

• M&A Deal of the Year – American Lawyer 2015 – Algerian Fonds National d’Investissement (FNI) in its acquisition of a 51% stake in Orascom Telecom Algérie (Djezzy).
• Ardagh on its acquisition of beverage can manufacturing assets and support locations in Europe, Brazil and the United States from manufacturing giants Ball Corporation and Rexam for $3.42bn.
• Banco Comercial Português in its sale of Millenium Bank to Piraeus Bank.
• M&A Deal of the Year – IFLR Americas Awards 2016 – The Dow Chemical Company in connection with the French portion of its worldwide divestment of a significant part of its chlorine value chain.
• Florac in connection with various private equity transactions, including:
  - its joint acquisition with L Capital of Groupe SMCP and the subsequent sale of Groupe SMCP to KKR,
  - its acquisition and subsequent sale of BricoPrivé,
  - its acquisition of a stake in the TCR Group from Chequers Capital (Belgium),
  - its investment in Salto,
  - its investment in the Sani and Ikos resorts alongside Oaktree (Greece and Spain),
  - its investment in Experienced Capital,
  - its investment Les Domaines de Fontenille,
  - its investment in GrandiStazioni (Italy),
  - its investment in Fusalp,
  - its investment in Spinecap,
  - its investment in Padi (US), and
  - its investment in Samson & Surrey (US).
• Lafarge in its sale of Ciments Guyanais to Argos.
• Nokia in its acquisition of Withings and in the sale of its Digital Health business.
• Novartis on its $3.9 billion acquisition of Nasdaq-listed Advanced Accelerator Applications.
• Ormat Technologies Inc. in its acquisition of Géothermie Bouillante SA.
• Siparex on its acquisition of a significant minority stake in NG Travel.
• Siparex on its investment in Batibig Group via its investment fund Siparex ETI 4.
• Société Générale in connection with various acquisitions and divestments around the world including:
  - in Poland, the sale of Euro Bank to Bank Millennium,
  - in the United Kingdom, the acquisition of BHF Kleinwort Benson,
  - in Germany, the acquisition of Gefa Bank and ALD,
  - in Greece, the acquisition and the subsequent sale of General Bank of Greece,
  - in Norway, the acquisition of Elcon Finans AS,
  - in France, the sale of ECS to Econocom,
  - in Brazil, the acquisition and the subsequent sale of Banco Pecunia.
• Vivendi in the acquisition of a 60% stake in Havas.

• According to Legal 500 EMEA, a client mentioned that the team is "very professional, efficient and responsive. Guillaume Isautier combines excellent legal skills with great efficiency and a commercial approach." (2020)
• According to Chambers Global, clients describe him as a "trusted adviser with a 360-degree approach to his clients' best interests,’" also reporting him to be "a refined negotiator." (2020).
• Clients tell Chambers Global that "the trust and the quality of our relationship comes from his thoroughness in his work," adding: "He is experienced and very involved in the cases." (2019).
• Sources further underline in Chambers Europe, "You feel you are the only client - he is very dedicated and fully available." (2018)
• According to Legal 500, Guillaume Isautier has "impeccable negotiation tactics and is instrumental in bridging the parties’ opposing interests". (2018)
• In Chambers Global, clients are full of praise for Guillaume Isautier's high level of customer service, finding him to be dedicated and available to his clients. (2018)
• Clients tell Chambers Global that Guillaume is "an absolutely fantastic lawyer, rigorous, professional and available" (2016) and that: "Guillaume knows our group very well, understands and anticipates its needs and delivers top-quality service with the right mix of technical and commercial skills." (2017)
• According to Chambers Global, Guillaume Isautier is "very well prepared and keen to find compromises between the various parties." One interviewee commented: "He was excellent - he gives real advice and from an operational point of view he anticipates the next stages of the transaction very well." (2015)