Market capitalisation is the total value of a company's outstanding shares, calculated by multiplying the share price by the number of shares. For an exchange, it's the sum of all listed companies' market caps. The NGX's total market cap sits around N55 to N60 trillion, but that headline figure disguises extreme concentration: a handful of stocks account for most of the value.
The Nigerian Exchange quotes its total market capitalisation daily, and it's one of the most commonly cited statistics about the Nigerian stock market. But the raw number can be misleading. A market cap of N55 trillion sounds substantial, but it's only around $35 billion at current exchange rates, making the NGX smaller than many individual US companies.
More importantly, market cap measures the total value of all outstanding shares, not just the ones available for trading. When a company's founding family holds 70% of shares and never sells, those shares are included in market cap even though they'll never appear on the order book. This distinction between total market cap and free-float market cap matters enormously for index construction and investment decisions.
The NGX is extremely top-heavy. Dangote Cement, MTN Nigeria, Airtel Africa, BUA Cement, BUA Foods, and the top banking names regularly account for 60% to 70% of total market capitalisation. That means the ASI's movements are overwhelmingly driven by a small number of stocks.
This concentration has practical consequences. When Dangote Cement rises 5%, it can move the entire ASI even if most other stocks are flat or down. An investor tracking the ASI is effectively making a concentrated bet on a few large companies rather than getting broad market exposure. For index construction, this concentration problem is a major reason why alternatives to simple market-cap weighting, such as free-float weighting or equal weighting, produce materially different results in Nigeria.
The ASI uses full-capitalisation weighting, meaning each stock's weight in the index equals its total market cap divided by the sum of all market caps. This approach counts every share, whether or not it's available for public trading. The result is an index that can overweight stocks with large strategic holdings and underweight stocks with highly liquid, actively traded shares.
Venoble's VNG-EQB index addresses this by weighting constituent stocks by free-float market cap, using only shares that are genuinely available for trading. The difference is significant. A stock where insiders hold 80% of outstanding shares gets an 80% haircut in VNG-EQB relative to its ASI weight. This produces an index that more accurately represents the investable opportunity set for portfolio managers.
Market capitalisation tells you one thing: how much the market values a company today. It doesn't tell you whether that valuation is justified, whether the shares are liquid, or whether the company's earnings support the price. Two N100 billion companies can be vastly different investments if one trades millions of shares daily and the other barely trades at all.
For Nigerian investors, always look beyond the market cap headline. Check the free float, the average daily trading volume, and the P/E ratio. A stock might rank in the top 20 by market cap but be practically uninvestable because 90% of shares are locked up. That's a common situation on the NGX, and it matters far more than the headline market cap figure suggests.
The NGX's total equity market capitalisation fluctuates with share prices but has ranged between N55 trillion and N65 trillion in recent years. In dollar terms, that's roughly $33 to $40 billion at current exchange rates, making it smaller than individual companies like Nvidia or Apple. The figure includes all outstanding shares, not just those available for public trading, so the investable market cap is considerably smaller.
Dangote Cement, MTN Nigeria, Airtel Africa, BUA Cement, and BUA Foods typically rank as the five largest companies. Together with the top banking names (Zenith, GTCO, Access, UBA), the top 10 stocks account for roughly 60% to 70% of total market capitalisation. This concentration means the ASI's daily movement is driven by a small number of names, and broad market exposure through the ASI isn't as diversified as it appears.
Several factors contribute. Nigeria's economy, while Africa's largest, has a GDP of around $370 billion, far smaller than developed economies. Many large Nigerian businesses aren't listed. The naira's depreciation has shrunk dollar-denominated market cap significantly; a stock unchanged in naira terms has lost substantial dollar value. And historically low market participation, both domestic and foreign, has kept valuations compressed relative to other frontier and emerging markets.