Oliver Assersohn
Oliver Assersohn

Oliver Assersohn

Call: 2003

"clearly outstanding"

Financial Services, Chambers and Partners

Overview: Oliver is a “truly excellent barrister” and “skilled advocate” who relishes trial advocacy, particularly cross-examination and “will work tirelessly in support of the client’s case”. He specialises in commercial matters and particularly in financial services, including regulation, for which he has been ranked by both Chambers & Partners and Legal 500 for many years.

Commercial/ Chancery litigation: A “financial services and banking specialist who has a wealth of expertise in the area”  with “... a broad chancery and commercial practice…He is incredibly diligent and hard-working, and continues to impress with his technical knowledge.” (Chambers & Partners). Also ranked by Legal 500 in commercial litigation, financial services and in the separate category of banking and finance and described as ‘Highly personable and a dream to work with – slots into the team very well and a tremendous team player.’ His experience includes:

  • Acting on behalf of purchasers of an IFA business suing the sellers for breach of warranty. Largely on the basis of cross-examination, successfully argued at a trial of a preliminary issue that various breaches of warranty were wilfully concealed and so the claim could proceed (Liberty Partnership Ltd v Tancred & Anr [2018] EWHC 2707 (Comm);
  • Successfully argued on behalf of a liquidator of a money-lending business that the assignment of the loan book should be set aside (Barons Finance Ltd v Barons Bridging Finance 1 Ltd & Ors [2018] EWHC 496 (Ch) (appeal dismissed by the Court of Appeal [2019] EWCA Civ 2074);
  • Acted for a number of years for the second largest organisation in Ethiopia which successfully defeated a US$30m claim on grounds of forum non conveniens (Court of Appeal judgment, Mengiste v EFFORT & Ors [2017] EWCA Civ 1326).

Financial services regulation: Previous accolades in the directories include: a “highly regarded junior”; an effective advocate”; and, someone who provides “excellent” written work and “clear and practical advice”. 

  • Oliver was seconded to the Regulatory Decisions Committee of the FSA (now FCA) therefore providing him with a valuable insight into how contested enforcement actions are approached;
  • He has acted in a number of the leading cases including, acting for a brokerage in the first ever case to challenge the FCA’s assessment of penalty following a focused resolution agreement (FCA v Linear Investments [2019] UKUT 0115 (TCC)) and advising in a number of high-profile investigations against both individuals and firms (example matters are set in the “areas of experience” section);
  • He is the editor of the Decision Procedure and Penalties Manual Commentary in Butterworths Financial Regulation Service.

Arbitration and international law: Oliver is a member of the Swiss Arbitration Association and Associate Member of the Chartered Institute of Arbitrators and his work includes:

  • Acting on behalf of an African State defending a US$300,000,000 claim for alleged breaches of a bilateral investment treaty concerning a construction project. Case involved cross-examination of a number of witnesses as to fact and liability including in respect of the claimant’s DCF analysis;
  • Numerous cases for states in respect of a number of litigation issues including claims involving questions of state immunity (e.g. instructed at first instance and for the first appeal in the leading case of Jana v Libya);
  • An alleged breach of a commercial arbitration agreement by solicitors acting for one party reporting the matter to their regulator.

Oliver is a DIFC (Dubai) Part II registered practitioner and author of the forthcoming practitioner text, Financial Services Law in the DIFC and ADGM.

Further information: Please see sections below for examples of Oliver's work. If any further information is required please do not hesitate to contact one of Oliver’s clerks or, if an existing client, to telephone Oliver direct in Chambers or on his mobile.

Areas of experience

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  • Arbitration

    Two ongoing cases that Oliver is working on are cited below by way of example:

    A Construction Company v an African State

    Instructed initially as sole counsel and subsequently leading Tom Stewart Coats on behalf of an African State defending a US$300,000,000 claim for alleged breaches of a bilateral investment treaty.

    Dispute arising from settlement

    Instructed on behalf of a financial services firm facing allegations of a breach of a settlement agreement.

  • Aviation

    On Tuesday 30 April, Oliver joined other speakers from XXIV in hosting a seminar on the grounding of Boeing’s 737 Max aircraft which explored:

    • The problem with the Max 8 and 9 explained
    • The impact on sale purchase and finance agreements – full / partial frustration
    • The effect on operating and finance leases, on which Oliver spoke with Edward Cumming QC
    • Damages for grounded aircraft – direct and indirect losses


    Provided assistance to leading airline in respect of inaccurate media reports about performance.

  • Banking and Financial Services

    Financial Services

    A core area of Oliver’s practice several examples of regulatory cases are provided below [for banking cases please see following section]:

    FCA v A CEO (RDC): Defending the former CEO of a company in liquidation (against a QC). The FCA’s case is that the CEO was knowingly concerned in the company breaching various rules by making false statements to the market and, among other things, failing to act with integrity.

    Firm X v FCA (Regulatory Transactions Committee (“RTC”), UT, 2021: Acted for firm subject to FCA requirements which would have had catastrophic consequences for its business. Argued against requirements before RTC. Urgently drafted applications for suspension of those requirements and privacy which were successful before the UT. Led at the UT and conducted oral advocacy on an important point.

    FCA v Firm Y (RDC, 2021): The FCA sought to impose an immediate variation of my client’s permission which would have destroyed its business. A negotiated resolution was not possible. On an urgent basis, successfully argued against the variation before the RDC.

    FCA v Linear Investments, Upper Tribunal (6 March 2019): Acted for a brokerage before the Regulatory Decisions Committee and then before the Upper Tribunal in the first ever case to be referred to the Upper Tribunal in which a firm had agreed a focused resolution agreement but disputed the FCA’s proposed level of penalty.

    Zai Corporate Finance Limited v (1) The AIM Disciplinary Committee (2) London Stock Exchange [2017] EWCA Civ 1294: Acted as sole counsel on behalf of Zai Corporate Finance Limited, a nomad facing disciplinary proceedings brought by the ADC judicially reviewing a decision of the AIM Disciplinary Committee.

    FCA v W

    Acting for brokerage and CEO subject to FCA investigation in respect of alleged part in an alleged fraud of several hundred million pounds.

    X v FCA

    Acted for individual subject to FCA enforcement investigation and alleged to have participated in large scale and serious conspiracy.

    Y v FCA

    Recently acted for individual applying to lift a prohibition order on an individual.

    Z v A Bank

    Advising compliance officer of a major global financial institution in respect of her whistleblowing and subseqient disciplinary proceedings in context of wider regulatory investigation.

    A company seeking investment: Advised a company that had developed a cutting edge technology whether or not their prospectus to investors and which had been used to raise several million pounds was misleading and in breach of ss. 89 and 90 of the Financial Services Act 2012


    After secondment to the Regulatory Decisions Committee of the FSA, continued to advise the Committee in a variety of cases. For example, he advised the Committee in FSA v (1) Visser (2) Fagbulu in which a ban and £2.1m fine were imposed on a hedge fund chief executive and chief financial officer for deceiving investors and market abuse.


    A lender v X 

    Acted for a lender bringing proceedings against a borrower in relation to a £4m mortgage. The borrower was seeking to avoid liability by (among other things) arguing that the loan was made in breach of the Financial Services and Markets Act (2000) and is therefore unenforceable. Settled during opening speeches.

    Interest rate swap mis-selling claims

    Acted in a large number of interest rate swap mis-selling claims against banks. Represented individuals and companies in pursuing compensation through the courts and advising on aspects of the FCA ordered redress scheme. In addition to the familiar contractual, common-law and statutory causes of action he has been involved in cases alleging negligence in relation to the implementation of the FCA Redress Scheme.

    Y Ltd v A Bank

    Acted for a company seeking to bring Holmcroft style judicial review proceedings of the actions of an independent reviewer.

    Z and the LIBOR investigation

    Instructed on behalf of a party that has been investigated in relation to the investigation into the manipulation of LIBOR in the context of potential civil claims.

  • Commercial Litigation

    Oliver is instructed in a number of ongoing matters in the High Court and examples of past work are cited below.

    Shop Direct v The Official Receiver [2022] EWHC 1355 (Comm)

    Oliver Assersohn acted for Shop Direct as junior counsel in which the Commercial Court granted a declaration in favour of Shop Direct Finance Company, to the effect that where the Official Receiver brings a payment protection insurance (PPI) claim acting as trustee in bankruptcy, it is the OR’s knowledge (actual or constructive) which is relevant for the purposes of the Dispute Resolution: Complaints Sourcebook (DISP) limitation rules, not the knowledge of the bankrupt.  The decision has potential industry-wide implications in relation to the large number of Complaints which the OR has sought to make in respect of PPI policies held by persons later made bankrupt.

    Akhmedova v Akhmedov & Ors

    Instructed close to trial by son being sued by his mother for c. US$100m. Complex legal issues re s. 423 Insolvency Act (1986) and s. 37 Matrimonial Causes Act (1973). Case highly sensitive and attracted significant press attention. As sole counsel, successfully argued at the search order return date (against a QC) that the propriety of the order should be examined at trial together with questions of costs (which the Claimant sought in the sum of £242,000) ([2020] EWHC 3006 (Fam)). Led at the subsequent trial [2021] EWHC 545 (Fam).

    Barons Finance Ltd v Barons Bridging Finance 1 Ltd & Ors, Court of Appeal [2018] EWHC 496 (Ch)

    Acting for joint liquidator in respect of a declaration an assignment was void under s. 127 of the Insolvency Act 1986 (“IA”) and that it should be set aside under s. 238 and s. 423 of the IA.

    Mengiste & Anr v EFFORT & Ors [2017] EWCA Civ 1326: Acted on behalf of defendants facing a $30m claim who successfully disputed jurisdiction grounds of forum non conveniens.

    X v Brokerage House (settled after pleadings and mediation)

    Recently acted for claimant in High Court claim alleging breach of contract, negligence and the FCA rules in relation to the brokerage house’s decision to (among other things) follow the instructions of a person to whom the claimant had granted third party authority and which resulted in the loss of almost the entire sum invested.

    Y v Z 

    Claim by major financial institution against another in respect of unpaid commission payments which the defendant refused to pay on the basis that to do so would breach the FCA Rules (they had not been disclosed by the defendant to its customers).

    Mengiste & Anor v Endowment Fund for the Rehabilitation of Tigray & Ors [2014] EWHC 4196 (Ch)

    Following the decision referred to above and the claimant’s subsequent application in Ethiopia, represented the defendants as sole counsel in successfully resisting the claimants’ application to lift the stay in this US$20m claim. The claimants currently have permission to appeal following an oral hearing before the Court of Appeal on condition they pay the defendants £200,000 in costs.

    Mengiste & Anr v EFFORT & Ors [2013] EWHC 1718

    Acted for the defendants who were being sued for $20m by the claimants who allege that the defendants obtained a judgment in Ethiopia by fraud. The defendants applied to stay the claim on the grounds of forum non-conveniens and the central issue has been whether or not there is cogent evidence that the claimants will not receive justice in Ethiopia. The claim was stayed on grounds of forum non-conveniens pending the Claimants being allowed time to make an application in Ethiopia. The case involved a range of subsidiary issues, most notably whether an expert witness in fear of his life could remain anonymous ([2012] EWHC 2782 (Ch)). Other reported decisions as part of the EFFORT litigation included: [2013] EWHC 598 (Ch) (22 March 2013); [2013] EWHC 856 (Ch) (25 March 2013); EWHC 857 (Ch) (26 March 2013); EWHC 1087 (Ch) (1 May 2013); EWHC 1003 (Ch) (14 August 2014).

    EFFORT & Ors v Rylatt Chubb [2013] EWHC 1003

    Acted for EFFORT in an application for wasted costs against the claimants’ solicitors relating to their choice of expert for the underlying action. The matter was appealed to the Court of Appeal.

    The Great Estates Group Limited v Digby [2011] EWCA Civ 1120, [2011] 43 EG 104(CS)

    Acted for the vendor of a private home who was sued by an estate agent who claimed that he was instructed as a sole agent and that he was entitled to damages for loss of the chance of earning commission when the sale of the property was not arranged through him. Successfully argued at first instance that the contract could not be enforced because the agreement did not comply with the Estate Agents Act (1979). The claimant appealed to the Court of Appeal, who by a majority (Lord Justice Lloyd dissenting) upheld the first instance decision. One of several estate agency cases undertaken.

  • Crypto and digital assets

    Oliver is co-author of the disputes chapter in Crypto and Digital Assets Law and Regulation published by Sweet and Maxwell in December 2023.

  • Hedge Funds & Structured Investment Vehicles

    Oliver’s grounding in financial services regulation and commercial litigation makes him well placed to handle disputes in respect of hedge funds and structured investment vehicles.

    Oliver has advised a number of investment vehicles in recent years and was previously instructed by the Regulatory Decisions Committee of the FSA in FSA v Mercurius Capital Management, FSA v Visser and FSA v Fagbulu. The case involved a number of important issues and resulted in what was at the time the biggest fine imposed on an individual for market abuse.

  • Insolvency

    Barons Finance Ltd v Barons Bridging Finance 1 Ltd & Ors, Court of Appeal [2018] EWHC 496 (Ch)

    Acting for joint liquidator in respect of a declaration an assignment was void under s. 127 of the Insolvency Act 1986 (“IA”) and that it should be set aside under s. 238 and s. 423 of the IA.

    X v Y (Chancery Division, August 2017)

    Acted for trustee in bankruptcy in obtaining an urgent freezing injunction before Mr. Justice Mann and instructed in the substantive underlying claim for breaches of the IA 1986.

    X v Z (2016)

    Instructed on behalf of financial institution in bankruptcy proceedings against a debtor.

Other information

  • Recommendations

    “He is great technically and is also very approachable and client-friendly.” “He is often in the high-profile, reported cases.” Financial Services, Chambers & Partners 2024

    ‘Oliver is an outstanding team player and brings commerciality as well as excellent analytical skills to the team. He is a go-to counsel for financial services regulatory matters.’ Financial Services Regulation, The Legal 500 2024

    Oliver is incredibly intelligent and has a particularly effective written style. He is a real team player and can be depended on in high-stakes litigation.’ Commercial Litigation, The Legal 500 2024

    ‘Oliver is an outstanding team player and brings commerciality as well as excellent analytical skills to the team.’ Banking and Finance, The Legal 500 2024

    “Oliver Assersohn is regarded very highly.” “He is very user-friendly and very experienced in financial services regulation.” “He is extremely knowledgeable about financial regulation in the UK and is clearly outstanding.” Financial Services, Chambers & Partners 2023

    “Oliver is very pleasant to work with and extremely personable. He is bright and committed; and understands how the FCA thinks. He is a robust advocate when needed.” Financial Services Regulation, Legal 500 2023

    “Technically brilliant, very hard working and a delight to work with.” Banking and Finance, Legal 500 2023

    Amiable and smart he produces superb written work and is a considered and impressive advocate. Wonderful to have in your team.” Commercial Litigation, Legal 500 2023

    “He’s technical but also sensitive to business and commercial implications – he weighs in in a way that furthers business goals.” “An ambitious and skilled advocate.” Financial Services, Chambers & Partners 2022

    “Oliver takes ownership of a case from the outset and will work tirelessly in support of the client’s case. He is very bright, and has significant FCA expertise.” Financial Services Regulation, Legal 500 2022

    “A superbly able junior, if there is an answer to a problem he will find it.” Banking & Finance, Legal 500 2022

    “Oliver has a rare mix of commercial acumen, empathy and wide-ranging communication skills which enable productive engagement at all levels.” Commercial Litigation, Legal 500 2022

    “An impressive specialist in FCA enforcement-related matters.” “He’s very responsive, very easy to deal with and the quality of his advice is also very good.” Financial Services, Chambers & Partners 2021

    “Highly personable and a dream to work with – slots into the team very well and a tremendous team player.” Banking & Finance, Legal 500 2021

    “Technically outstanding, and very hard working and responsive – he also has very sound client management (expectation management and empathy) skills.” Commercial Litigation, Legal 500 2021

    “Excellent attention to detail, good analytical skills coupled with regulatory knowledge and experience.” Financial Services, Legal 500 2021

    “He is easy to get along with and thorough in his advocacy, and pitches his arguments in a respectful way to the tribunal.” Oliver is “very accessible, very user-friendly and works really well as part of the team.” Financial Services, Chambers & Partners 2020

    “Very responsive and hardworking, his input is always measured and valuable”. Banking and Finance, Legal 500 2020

    Bright, well informed and has good judgement”. Financial Services, Legal 500 2020

    “A highly regarded junior who is an expert at handling complex issues relating to mis-sold investments and breaches of the perimeter. Having been on secondment to the FCA, he has highly valuable insight into the workings of the regulator….”Approachable, helpful and diligent.” “A credible and hard-working advocate.” Financial Services, Chambers & Partners 2019

    “Very good for fraud and financial regulatory investigations.” Financial Services, Legal 500 

    “Highly rated for banking and financial services disputes.” Banking and Finance, Legal 500

     “His written work is always excellent, he provides clear and practical advice and he deals with clients in a very empathetic manner.” Financial Services, Chambers & Partners 2017

    “Technically bright, hardworking, a team player and approachable.” Business and Regulatory Crime, Legal 500 2016

    “A truly excellent barrister, who knows the ins and outs of FCA regulations.” Banking and Finance, Legal 500 2016

    “A financial services and banking specialist who has a wealth of expertise in the area. He has a broad chancery and commercial practice…He is incredibly diligent and hard-working, and continues to impress with his technical knowledge.” Chambers & Partners 2016

    “He has a very innate feel for the regulators’ expectations and is very good at the detail. He understands the issues and is very diligent and analytical.” Chambers & Partners 2016

    “Very bright, exceptionally hardworking, personable and very practical. He really understands the FCA’s enforcement process.” Chambers & Partners 2015

    “He is calm, knowledgeable, diligent and keen to assist. A pleasure to work with.” Chambers & Partners 2015

    “Extremely well regarded for financial services and FCA regulatory issues.” “The barrister to go to with challenging issues.” Legal 500 2015

     “An absolute delight to work with.” Chambers & Partners 2014

     “Highly experienced in regulatory and FCA related matters.” Legal 500 2014

    “A financial services specialist.” Legal 500 2014

    “First rate.” Chambers & Partners 2013

    “An enviable reputation as a leading junior in financial services law.” Chambers & Partners 2012

    “The ‘knowledgeable, calm and authoritative’ Oliver Assersohn is recommended for contentious financial services work, where ‘his experience is almost unique’.” Legal 500 2012

    “Highly diligent.” Chambers & Partners 2011

    “Invaluable knowledge of the FSA disciplinary process.” Legal 500 2011

    “Understands how the regulator lives and breathes.” Chambers & Partners 2010

  • Publications
    • Co-author of the disputes chapter in Crypto and Digital Assets Law and Regulation (Sweet and Maxwell, December 2023).
    • Articles in numerous publications on financial services and banking matters (e.g. JIBFL November 2015 (the proposed EU Banking Union), JIBFL July/ August 2017 (Financial services law as a sword: cutting down contracts).
    • Co-author the chapter of COMBAR’s paper on Brexit (January 2017) entitled “MiFID, MiFID II and MiFIR: (1) Passporting and Equivalence Regimes; (2) Brexit effect on UK financial services dispute resolution” (December 2016).
    • Editor of the Decision Procedure and Penalties Manual Commentary in Butterworths Financial Regulation Service (c. 40,000 words) (published March 2015).
  • Lectures and seminars

    Oliver is regularly invited to give talks to solicitors firm and take part in panel discussions (for further details please contact Oliver’s practice management team by email to clerks@xxiv.co.uk).

  • Appointments & Memberships
    • Member of FSLA (founding member)
    • COMBAR
    • Associate member of Chartered Institute of Arbitrators.
    • Advocacy trainer for Middle Temple.
  • Awards
    • Queen Mother Fund Scholarship (2002)
    • Blackstone Entrance Exhibition (2002)
    • Queen Mother Fund Scholarship (2001)