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Portrait of Thomas Sonnenberg

Dr. Thomas Sonnenberg


CMS Hasche Sigle
Kranhaus 1
Im Zollhafen 18
50678 Cologne
Languages German, English, French

As a highly regarded expert on international corporate structures, Thomas Sonnenberg specialises in the field of strategic compliance and corporate governance. His practice also covers corporate and stock corporation law, M&A and private equity transactions as well as finance, banking and related regulatory matters.

Before joining CMS, Thomas had been at private bank Sal. Oppenheim for almost 20 years, eight of which as general counsel. He subsequently joined industrial services provider Ferrostaal as general counsel in 2010, followed by general counsel, chief compliance officer and head of the management and supervisory board office positions at construction group Hochtief in Essen. Thomas then worked for private equity investor Triton as general counsel and head of corporate governance before joining CMS in 2016.

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Relevant experience

  • Advising an international conglomerate in the consummation of internal investigations
  • Advising on the group-wide introduction of monitoring and control processes in connection with the combat of bogus employment and improper hiring-out of employees
  • Advising a medium-sized business in connection with reorganization of internal export control
  • Advising several businesses on anti-money laundering organization, in particular for distribution activities in Eastern Europe
  • Advising the buyer on the acquisition of the private equity fund-of-fund business of a major German bank
  • Advising an international mechanical engineering group on intra-group mergers
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  • „Kommunikation als Schlüssel zu erfolgreichem Compliance-Management – Sieben Thesen“, Compliance-Berater 2019, 1 (Co-authors: Christina Ritzenhoff, Prof. Dr. Martin Schulz), („Communication as a key for successful compliance management – seven thoughts“)
  • „Non-compliance in China – Obligations and Risks for German Employees, German Parent Companies and their Management”, in: Senff/Zhang, “Governance, Risk and Compliance Management in China”, 2018
  • „Compliance-Systeme in Unternehmen”, JuS 2017, 917 („Compliance-systems in commercial businesses“)
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  • 1992: Second state examination in law, Cologne
  • 1989: PhD (Dr. iur. utr.), University of Cologne
  • 1987: First state examination in law, University of Cologne
  • 1982 - 1987: Law studies at the University of Cologne
  • 1980 - 1982: Apprenticeship in banking
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Get in contact with


CMS ad­vises CAM Al­tern­at­ives on mer­ger with Altamar Cap­it­al Part­ners
Co­logne – As­set man­agers CAM Al­tern­at­ives and Altamar Cap­it­al Part­ners, who spe­cial­ise in private equity, real es­tate and in­fra­struc­ture, have joined forces to form a new com­pany called Altamar CAM...
CMS ad­vises BE In­vest­ment-Part­ners and Wun­dex on ma­jor­ity sale to capiton...
Co­logne - The private equity in­vestor capiton has ac­quired a ma­jor­ity stake in the Wun­dex Group, a lead­ing full-ser­vice pro­vider for wound care in Ger­many. Capiton ac­quired the shares in the course of...
CMS ad­vises on­line broker Next­mar­kets on Series B fin­an­cing round worth...
Co­logne – On­line broker Next­mar­kets has re­ceived USD 30 mil­lion in a Series B round of fin­an­cing. The ad­di­tion­al cap­it­al is ear­marked for ac­cel­er­at­ing the fintech’s European ex­pan­sion and es­tab­lish­ing...
Glob­al league for es­ports es­tab­lished: CMS ad­vises Elec­tron­ic Sports League...
Co­logne – Fol­low­ing two years of ne­go­ti­ations, the Louvre Agree­ment has now es­tab­lished the first glob­al league between sig­nat­or­ies Elec­tron­ic Sports League (ESL) and the twelve lead­ing in­ter­na­tion­al...
CMS ad­vises ERIKS on the sale of its sub­si­di­ary Siek­mann Eco­n­o­sto
CMS ad­vises ERIKS on the sale of its sub­si­di­ary Siek­mann Eco­n­o­stoDuessel­dorf – ERIKS N.V. sells its Ger­man sub­si­di­ary Siek­mann Eco­n­o­sto GmbH & Co. to Ne­way Valve (Su­zhou) Co., Ltd. The parties have...
August 2019
Avoid­ing ugly head­lines
Com­pli­ance is a key re­quire­ment for the next stage in the rap­id glob­al de­vel­op­ment of es­ports. Ig­nor­ing the need for an ef­fect­ive com­pli­ance, eth­ics and gov­ernance sys­tem would be an ex­pens­ive and pain­ful...
CMS ad­vises CAM Private Mar­kets on ac­quis­i­tion of DB Private Equity GmbH...
Co­logne – The Co­logne-based CAM Group has ac­quired all the shares in DB Private Equity GmbH from Deutsche Bank. The pur­chase price was not dis­closed. The DB Private Equity di­vi­sion handles in­vest­ments...
CMS strengthens com­pli­ance prac­tice with Dr Rain­er Runte
Mu­nich – Dr Rain­er Runte, a dir­ect­or of Freseni­us Med­ic­al Care AG & Co. KGaA for many years, is join­ing CMS with ef­fect from 1 June 2018. Dr Runte will work as of coun­sel in the Cor­por­ate prac­tice area...
CMS ad­vises STRA­BAG on suc­cess­ful agree­ment with ISS on trans­fer of more...
Co­logne – STRA­BAG Prop­erty and Fa­cil­ity Ser­vices GmbH (STRA­BAG PFS) has signed an agree­ment with ISS Fa­cil­ity Ser­vices Hold­ing GmbH (ISS) re­gard­ing the con­tin­ued em­ploy­ment of more than 3,000 work­ers...
11 July 2017
Ger­many: New law makes con­fis­cat­ing pro­ceeds of crimes easi­er
On 1 Ju­ly 2017, the new Act to Re­form Crim­in­al Law on Pro­ceeds of Crime be­came ef­fect­ive (the “Act”). The act trans­posed the EU Dir­ect­ive on the Freez­ing and Con­fis­ca­tion of In­stru­ment­al­it­ies and...
CMS ad­vises lab ser­vice pro­vider SYN­LAB on ac­quis­i­tion of AL­con­trol
Mu­nich – The SYN­LAB Group has signed a pur­chase agree­ment to ac­quire the AL­con­trol Group, a European pro­vider of test­ing ser­vices in the en­vir­on­ment­al sec­tor. This ex­pands SYN­LAB’s ca­pa­city with re­gard...