When you see a headline saying "the Nigerian stock market rose 2% today", the reporter is almost certainly referring to a movement in the NGX All Share Index. The ASI is the single most important benchmark for Nigerian equities — understanding what it measures, how it is calculated, and what it does and does not tell you makes it a far more useful reference point.
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Definition
The NGX All Share Index (ASI) is the main benchmark index of the Nigerian Exchange Group (NGX). It tracks the price performance of all domestic ordinary shares listed on the NGX and is the most widely cited indicator of overall Nigerian stock market performance.
The NGX ASI is a market-capitalisation-weighted index of all domestic ordinary shares listed on the main board of the NGX. This means larger companies (by market cap) have a proportionally larger influence on index movements. If MTN Nigeria or Dangote Cement rises significantly, the ASI moves more than if a smaller, less liquid company rises by the same percentage.
The NGX ASI uses a base value and is updated in real time during market hours based on current share prices and total shares outstanding for each constituent company. The formula weights each company by its market capitalisation — so index movements reflect the aggregate performance of listed companies weighted by their size.
Investors and fund managers use the NGX ASI to benchmark performance. If your equity portfolio returned 15% in a year and the ASI returned 20% in the same period, your portfolio underperformed the market benchmark. If a mutual fund manager consistently beats the ASI over multiple years, that is a meaningful result. The ASI gives you the most direct measure of what the "average" NGX equity investor experienced.
The NGX also publishes sector indices (NGX Banking Index, NGX Insurance Index, NGX Consumer Goods Index, NGX Industrial Goods Index), as well as the NGX 30 (top 30 companies by market cap and liquidity). These allow investors to track the performance of specific sectors or the largest, most liquid stocks separately from the broader market.
The ASI measures price performance — it does not include dividends. The "total return" version of the index (which reinvests dividends) gives a higher return figure over time. The ASI is also a historical measure — where the index has been tells you what already happened, not what will happen next. A rising ASI does not guarantee that any specific share will rise, or that the market will continue rising.
The current ASI level is published on the NGX official website (ngxgroup.com) and updated in real time during trading hours. It is also carried by Nigerian financial news sources and data services.
The NGX ASI includes all domestic ordinary shares listed on the exchange — the number changes as new companies list or existing companies delist. For the current count, check the NGX official website.
Because the ASI is market-capitalisation-weighted, small-cap stocks have minimal influence on the index. A small company can move 10% without materially affecting the ASI. Large-cap companies like the major banks, MTN Nigeria, and Dangote Cement have a much larger index impact when they move.
The NGX ASI includes all listed domestic ordinary shares. The NGX 30 tracks only the 30 largest and most liquid companies. The NGX 30 is sometimes more practical as a benchmark because it focuses on the most tradeable stocks, but the ASI provides the broadest market overview.
The standard NGX ASI is a price index — it reflects share price movements only and does not include the reinvestment of dividends. The total return version includes dividend reinvestment and gives a higher long-term return figure. For a fair comparison of long-term equity performance, the total return index is more accurate.
Important disclaimer
This page is for general information and educational purposes only. It does not constitute financial advice, investment advice, legal advice, or tax advice. The value of investments can fall as well as rise. Past performance is not a guide to future results. Seek independent regulated financial advice before making any investment decision. Shares Saver does not provide financial advice.
Shares Saver lets you buy and own NGX-listed shares directly in your own name through regulated broker execution.
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