The NGX All-Share Index — commonly abbreviated to ASI — is the headline measure of overall performance on the Nigerian stock market. When financial news reports that "the Nigerian stock market rose by X% this week", it is typically referring to the movement in the ASI. Understanding what the ASI measures, and what it does not tell you, is foundational knowledge for any Nigerian investor.
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Definition
The NGX All-Share Index (ASI) is the principal benchmark index of the Nigerian Exchange Group, tracking the price performance of all eligible ordinary shares listed on the exchange, weighted by market capitalisation.
The ASI is a market-capitalisation weighted index. This means that companies with larger market capitalisations have a greater influence on the index level than smaller companies. The index is calculated continuously during trading hours as share prices change. The base value of the index was set at 100 at inception. The current level represents the growth in total market value since that base date.
The absolute level of the ASI (e.g. 95,000 or 110,000) is less informative in isolation than the direction and rate of change. Investors typically focus on percentage changes over specific periods — one month, one year, five years — to understand how the overall market has moved. A rise in the ASI means that, on a weighted average basis, share prices on the NGX have increased. A fall means they have decreased on average.
The NGX publishes multiple indices in addition to the ASI. The NGX 30 Index tracks the 30 largest and most liquid stocks. Sector indices such as the NGX Banking Index, NGX Consumer Goods Index, and NGX Industrial Index track specific sectors. These provide more granular views of how different parts of the market are performing, which is useful for investors focused on particular sectors.
The ASI is used as a benchmark to measure portfolio performance — a portfolio that grew 15% in a year when the ASI grew 10% outperformed the market; one that grew 5% underperformed. It is also used in financial analysis, economic reporting, and investor communications. The ASI is not, however, directly investable — you cannot buy the index itself, only individual shares or ETFs that track specific groups of shares.
The current ASI level is published on the NGX website (ngxgroup.com), through licensed stockbroker platforms, and through financial news services covering Nigerian markets. The ASI is updated continuously during NGX trading hours (typically 10:00–14:30 WAT on trading days).
It measures the overall price performance of all eligible ordinary shares listed on the Nigerian Exchange Group, weighted by market capitalisation. It is the principal benchmark for the Nigerian stock market.
The ASI covers all eligible ordinary shares on the NGX. The NGX 30 Index covers only the 30 largest and most liquid stocks. The NGX 30 can move differently from the ASI if large-cap stocks perform differently from the broader market.
The current ASI is published on the NGX website (ngxgroup.com), through stockbroker trading platforms, and through financial data services covering Nigerian markets.
No. The ASI is an average weighted by market cap. Some individual stocks may fall while the index rises, and vice versa. The index reflects the aggregate market movement, not the performance of every individual company.
It is comparable in concept — like the S&P 500 in the US or the FTSE 100 in the UK, the ASI measures the aggregate performance of the home market. However, the underlying economies, market depths, and currency bases are different, so direct comparisons of performance numbers should be made with care.
The ASI is updated continuously during NGX trading hours. End-of-day values are published after the market closes.
Important disclaimer
This article 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. 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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