Arrow-Debreu securities are a type of financial instrument used in the context of contingent claims, representing a specific state of the world at a future time. Named after economists Kenneth Arrow and Gérard Debreu, these securities pay off only if a particular event occurs, allowing them to capture the uncertainty of future outcomes.
In practical terms, each Arrow-Debreu security corresponds to a state defined by specific conditions that exist at a future date. For example, if the security is tied to a particular economic condition, it will provide a payout only if that condition is met. This feature makes Arrow-Debreu securities valuable for hedging against risks and for allowing investors to trade on expectations of future states of the world.
These securities are widely discussed in theoretical finance and economics, particularly in the areas of general equilibrium theory and asset pricing. Their idealized version helps in understanding the pricing of more complex derivatives and risk management tools, ultimately serving to improve market efficiency by facilitating the allocation of risks.
