Oliver Assersohn is a commercial/ Chancery and regulatory barrister specialising in banking and financial services and is recommended by the foremost independent legal directories for financial services. Chambers & Partners describes him as “a highly regarded junior who is an expert at handling complex issues relating to mis-sold investments and breaches of the perimeter…An effective advocate…”. Previous editions said “an absolute delight to work with”, “…[his] written work is always excellent, he provides clear and practical advice and he deals with clients in a very empathetic manner” and 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.” Also ranked by Legal 500 for financial services and banking and finance who describe him as “…a truly excellent barrister…”.

Commercial/ Chancery work: A substantial element of Oliver’s work has a banking or financial services angle to it and he has acted for institutions, funds, family offices and individuals. In addition to an analysis of the contractual, equitable and common-law position Oliver is able to bring to bear his detailed knowledge of the Financial Services and Markets Act (2000), the regulatory regime more generally and the impact of the FCA rules on a civil claim. Oliver has also undertaken a broad range of non-financial services related commercial or Chancery cases for negligence and breach of contract as well as being instructed in insolvency claims, interlocutory applications and jurisdictional issues with particular experience of forum non conveniens issues.

Financial services work: Oliver acts for individuals and institutions subject to investigation by the FCA and is currently involved in assisting both firms and individuals facing both domestic and multi-jurisdictional investigations. He has extensive experience of market abuse and insider dealing issues and of advising investors, investment advisors and others in relation to investment schemes and other perimeter matters. Oliver was previously seconded to the Regulatory Decisions Committee of the FSA (which decides contested enforcement decisions) and advised the FSA in a number of cases as well as having been instructed by the enforcement division. He is the editor of the Decision Procedure and Penalties Manual Commentary in Butterworths Financial Regulation Services.

Arbitration and international work: 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. Also acted for states in respect of issues surrounding questions of state immunity and multi-jurisdictional commercial disputes. Associate Member of Chartered Institute of Arbitrators.


Please see sections below for examples of Oliver’s work.

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.

  • 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]:

    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 recent examples of past work are cited below.

    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.

  • 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.