Our service is not new, our approach is.


We focus on consistently delivering one thing: efficient solutions that get the deal done.

It's our process that's different. In only two years in business we have managed to become a market leader for our progressive approach.

We pride ourselves on being more agile, efficient and specialised than our competitors. One of our top priorities is to form a close-knit partnerships with our clients.


Our specialised offering, and deep experience in the corporate M&A and tax industries, coupled with our access to Castel’s infrastructure and platforms, equips us to deliver higher-quality, tailored services designed to specifically fit your needs.


Transact is a division of Managing General Agency (MGA) with offices in Amsterdam and London. Our skilled team of experts is comprised exclusively of M&A and tax lawyers.




Transact Risk Partners LLP is a division of Castel Underwriting Agencies Limited (Castel) – a regulated MGA. Our partnership with Castel allows us to focus on underwriting and our clients’ needs whilst they take care of the operational functions.


Transact has the resources to perform all the functions of an insurance company but outsources the provision of risk capital to insurers. We are therefore not a risk bearer, and instead, write insurance on behalf of other insurance carriers with whom we have a Binding Authority Agreement.

Transact receives full authority from a number of insurance markets to issue insurance on their behalf. By grouping capacity, this enables for larger limits of insurance coverage. Insurers commit risk capital on an annual basis through our Binding Authority Agreement. The list of our insurers is attached to every policy we issue and remains unchanged for the year.

Our current insurers are:






Sammy Shihab

Founding Partner


Sammy is a team player, with 10+ years of experience in the tax law and insurance industries. He’s known for finding innovative iterations to standard processes. Before founding Transact, Sammy worked at AIG, establishing their Benelux transaction division and becoming the first underwriter to focus on the region.

Prior to that he worked as a tax lawyer for PricewaterhouseCoopers (PwC). During his 7 years in the Melbourne offices and his 2 years in Jakarta, he specialised in M&A tax and international tax structuring. He assisted private equity and institutional clients on more than one hundred deals ranging from EUR 10m to EUR 15 billion in transaction size.

Outside of the office, he’s recognised for his hobby of swimming, often in (very cold) open water.



Herman van Aerts



Herman has been working as an M&A lawyer since 2006. He likes to find new solutions to old problems and has a pragmatic approach to “getting the deal done”.

Over the last decade, his focus has shifted from corporate law to legal advisory for M&A transactions and W&I business and is now an M&A underwriter himself. Before then, he fulfilled roles as a corporate lawyer and was involved in over 125 domestic and international transactions, ranging from small (EUR 5 million) to mid-size (EUR 150 million) in sectors like real estate, industrial, TMC, automotive and insurance.

When he’s not at work, he can be found playing the piano, playing tennis or cycling on his racing bike when it is not too cold.



Staffan Bos

Senior Tax Risk Underwriter


Staffan has been working as a tax lawyer since 2015. He’s known for his realistic and practical approach. He believes each case is unique and that there is a tax insurance solution to fit each client’s needs and circumstances.

Prior to joining Castel, Staffan worked for CMS in the tax practice group. He focused on direct tax, including corporate income tax, personal income tax and wage tax.  In addition to his role as tax advisor, he also assisted clients and underwriters with tax due diligence and tax insurance-related advice.

Outside of work, Staffan likes to ride his motorcycle or racing bike (even when it is cold) and enjoys recreational kickboxing.


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Francois Piquet

Senior M&A Underwriter


François has been working as an M&A professional since 2015. At Transact his focus are our French, Luxembourg and Belgium projects. His attention to detail and his ability to understand both legal and business aspects of a deal allow François to provide our clients with the strongest outcome.

Prior to joining us, François trained in M&A and Tax Law at a number of first class US & Magic Circle law firms subsequently joining Skadden Arps Slate Meagher & Flom M&A team in Paris and then Herbert Smith Freehills Paris office, working on a range of complex cross border corporate transactions, as well as on corporate governance and regulatory matters.

François passed the French Bar exam and graduated from ESSEC Business School with a Master of Science in Management (Corporate Finance and General Finance specialties in Paris and Global Manager in Asia Program in Singapore) and from Paris II Panthéon-Assas University with a Magister’s and a Master’s degrees in Business Law, a certificate of specialization in Tax Law and a Postgraduate diploma of Corporate legal Adviser (DJCE).

Outside of work, François enjoys playing golf, diving and taking pictures. François also teaches corporate finance, tax law and business law in a French business school.

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Valentijn Punt

M&A Underwriter


Valentijn is a M&A Underwriter at Transact Risk Partners. Previously, Valentijn worked in the M&A department of Deloitte Legal where he oversaw the due diligence process of buy- and sell side transactions and drafted different types of agreements in the context of acquisitions.

In addition, Valentijn has experience as consultant in clean technology venture capital investments. His background allows Valentijn to consider both the legal and commercial side of complex transactions and his experience in partnership formations enables him to deliver results based on the interests of all stakeholders involved.

Valentijn obtained an U.S. legal degree (juris doctor) from the New York University School of Law and is a member of the New York State Bar Association. Outside of work, Valentijn enjoys outdoor sports such as surfing, rock climbing, mountaineering, skiing, sailing and trail running. Additionally, he enjoys reading about physics, philosophy, history, and politics.



Pierre-Samuel Dahan

Tax and M&A Underwriter


Pierre-Samuel has been working as a trainee-lawyer at several international law firms in Paris since 2016. At Transact he’s particularly involved in most of our French and Belgium projects. His attention to detail and natural curiosity allow him to identify unique angles and perspectives that highlight unique opportunities.  

Prior to joining us, he worked in the CMS and Linklaters Paris offices, where he focused on corporate tax law in relation to private equity transactions and personal income tax. Pierre-Samuel passed the French Bar exam and graduated from the Sorbonne University with a Master’s degree in Business Law and another degree in Tax Law. In France.

Outside of work, you can find him playing the drums, practicing boxing or out in the Amsterdam forest, enjoying a run on a cold night.



Let’s talk

Call us or send your questions, comments or project details and we’ll get a conversation started.