What a stock exchange does and what an index measures

A stock exchange is a regulated marketplace where buyers and sellers meet to trade shares of listed companies. It is not a shop that owns the shares it displays, and it does not set the price of any company. Instead, it provides the rules, systems and oversight that let investors exchange securities with confidence. Companies that wish to have their shares traded must apply for listing and satisfy disclosure, governance and reporting requirements, so that investors have reliable information about what they are buying.

Trading happens during defined sessions. Orders are submitted through licensed dealing members and matched on the exchange's electronic platform, with prices forming from the balance of demand and supply. After a trade is agreed, settlement follows: the buyer pays and the seller delivers the shares, completing the transfer of ownership. Clearing and settlement arrangements sit behind the scenes to reduce the risk that one side of a trade fails.

What a market index measures

A market index tracks the aggregate performance of a selected group of listed companies. It is a statistical measure, not a tradable asset and not the price of any single share. Each index has a methodology: which companies qualify, how each is weighted, and how often the basket is reviewed. Because the constituents and their weights differ, indices can move in different directions on the same day.

• An index summarises the movement of many shares in a single figure.
• A share price reflects the market's view of one company alone.
• Weighting means larger constituents influence the index more than smaller ones.
• Index reviews can add or remove companies, changing what the measure represents.

How the NGX fits

The Nigerian Exchange operates as the country's principal securities marketplace, with listing rules, trading sessions and settlement processes governing how shares change hands. Its indices are constructed from companies listed on that exchange, so they reflect activity on that market rather than the wider economy or any other market. Contracts that reference an index track the measure and do not confer ownership of the underlying shares.

Understanding this distinction matters. An index reading tells you how a basket of companies has moved in aggregate; it says nothing about the merits of an individual share, and it is not a signal to act. Investors should read the index methodology and the constituent list before drawing conclusions from any movement in the measure.