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Simon Firth

Capital Markets Partner, London

“I specialise in derivatives, using my in-depth knowledge of the law and extensive experience of the market to provide clients with clear, commercially focused and definitive advice on highly complex legal issues.”


Professional experience

Education and qualifications


Simon is a leading authority on derivatives, specialising in the structuring and documentation of derivatives transactions and advising about issues arising in relation to derivatives and the financial markets generally.

Work highlights

Simon led the team advising the English administrators of the Lehman Brothers companies on their derivatives, repo and stock lending positions and has been involved in some of the market’s most significant cases involving derivatives. These include:

  • Lomas v JFB Firth Rixson, Inc., the leading case on the ISDA Master Agreement; and
  • Re Lehman Brothers International (Europe) (No.6), which established a number of important principles regarding the close-out provisions of the ISDA Master Agreement

He often advises market participants about issues arising in the credit derivatives market and was heavily involved in recent decisions of the ISDA Credit Derivatives Determinations Committee involving Novo Banco and iHeart Communications.

Currently, he is actively advising a range of financial institutions about the impact of the new margin rules for non-centrally cleared OTC derivatives transactions.


Professional experience

Simon is a Visiting Professor at the University of Law. He is also a member of the Financial Markets Law Committee, an independent committee of legal experts responsible for identifying issues of legal uncertainty in the wholesale financial markets.

Simon frequently writes and speaks about legal issues in the financial markets. He is the author of:

  • Firth on Derivatives Law and Practice, Sweet & Maxwell (looseleaf), the leading text book on English derivatives law; and
  • “The English Law Treatment of Lehman’s Derivatives Positions”, in Bank Failure: Lessons from Lehman Brothers, Oxford University Press, March 2017

Education and qualifications

Simon studied Jurisprudence at Christ Church, Oxford University.