A security is a tradable financial asset. The term commonly refers to any form of financial instrument, but its legal definition varies by jurisdiction. In some jurisdictions the term specifically excludes financial instruments other than equities and fixed income instruments. In some jurisdictions it includes some instruments that are close to equities and fixed income, e.g. equity warrants. In some countries and languages the term “security” is commonly used in day-to-day parlance to mean any form of financial instrument, even though the underlying legal and regulatory regime may not have such a broad definition.

In the United Kingdom, the national competent authority for financial markets regulation is the Financial Conduct Authority; the definition in its Handbook of the term “security” applies only to equities, debentures, alternative debentures, government and public securities, warrants, certificates representing certain securities, units, stakeholder pension schemes, personal pension schemes, rights to or interests in investments, and anything that may be admitted to the Official List.

In the United States, a security is a tradable financial asset of any kind. Securities are broadly categorized into:

  • debt securities (e.g., banknotes, bonds and debentures)
  • equity securities (e.g., common stocks)
  • derivatives (e.g., forwards, futures, options and swaps).