In securities trading, same-day affirmation (SDA) also known as T0 refers to completing the entire trade verification process on the same day that the actual trade took place, and was invented in the early '90s by James Karat, the inventor of straight-through processing, in London. Trade verification is carried out on the institutional side of the market between the investment manager and the broker/dealer. This process ensures that the parties are in agreement about the essential trade details. The three key steps in the verification process that Karat created are: