Stock Exchange Daily Official List (SEDOL) is an identifying code used to bring order and transparency to international stock markets. It is used mainly by financial institutions and industry professionals in the trading of securities on the London Stock Exchange and other smaller markets in the United Kingdom.

The code consists of seven characters, with the seven character being a weighted sum of the first six. It begins with the six alpha-numeric characters and ends with a checksum character. The code is assigned to every security that is traded on the London Stock Exchange and other smaller exchanges in the United Kingdom. The SEDOL Codes are maintained by a private organization, the London Stock Exchange (the LSE).

SEDOL stands for 'Stock Exchange Daily Official List'. Essentially, it is a unique identifier for each and every security that is available for trading on the London Stock Exchange.

The code is used by investors and traders to identify, locate, and accurately trade that security. When entering trades, SEDOL codes provide a standard pricing reference from which all interested parties agree on a security’s pricing and value.

SEDOL codes have significantly reduced trade costs and cut down on time needed to process trades and securities transactions. Investors and brokers can now quickly and accurately identify securities, resulting in greater efficiency in the marketplace. In addition, the SEDOL code helps protect against the risk of errors occurring in the process of trading a security.

The use of SEDOL codes is spreading not just throughout the United Kingdom but to other countries as well. This is due in part to the increased global competition among financial institutions and leading markets, which are beginning to understand the immense benefits SEDOL codes can bring to the financial market.

The SEDOL code breaking system is designed with a built-in algorithm that allows authorized users to rapidly recognize codes and make sure that the data is accurately stored and processed within the financial system. This feature has helped to ensure the integrity of the stock markets and further reduces the risk of fraud.

SEDOL codes are now the standard identifier for financial markets in the United Kingdom, and their widespread use is expected to aid in furthering their popularity in the global financial system.