The price band problem: Why NGX’s ±10% cap needs a proper farewell

There is a conversation happening inside Nigerian capital markets circles that probably deserves a wider audience.

It concerns something most retail investors on the Nigerian Stock Exchange have probably never thought about, and most institutional participants have quietly complained about for years.

It is the architecture of price formation on NGX.

And the diagnosis is not one problem. It is two, running simultaneously, feeding off each other. The first is the ±10% daily price band. The second is the rule that requires 100,000 shares to change hands before a stock price can move at all. Both need to go. Neither should go without a proper replacement.

Let us start with what the ±10% band actually is, because this is where the conversation tends to go wrong. It is not a circuit breaker in the way most people use that term. When people reference circuit breakers, they usually mean what the NYSE does in the United States or what the LSE does in the United Kingdom.

These are pause-and-resume mechanisms. In the US, the NYSE operates a three-tier market-wide circuit breaker system, where a 7% decline in the S&P 500 triggers a 15-minute halt, a 13% decline triggers another halt, and a 20% decline closes the market for the remainder of the day.

Crucially, the market reopens. Price discovery continues.

The US also runs a more surgical instrument called Limit Up-Limit Down, or LULD, for individual stocks. LULD prevents trades in individual securities from occurring outside specific price bands that update continuously throughout the trading day, with the bands set as a percentage above and below a reference price calculated from the average trade price over the immediately preceding five-minute period.

So the band moves with the stock. It is dynamic, market-referenced, and designed to accommodate genuine price discovery while slowing disorderly moves. If a stock breaches its band and the price has not corrected within 15 seconds, the exchange can declare a five-minute trading halt, after which trading resumes.

The LSE takes a similar approach. FTSE 100 stocks are protected by circuit breakers that pause trading if a price moves 8% above or below the stock’s opening price. Pause, not terminate. Research into the efficacy of single-stock circuit breakers on the LSE found that these mechanisms help prevent the transmission of poor market quality from a volatile stock to other stocks that continue to trade, with the occurrence of a single-stock circuit breaker leading to a statistically significant reduction in volatility and bid-ask spreads across the rest of the order book.

NGX’s ±10% band operates on an entirely different logic. When a stock hits its cap, it does not pause and reopen. It simply stops for the day. The session ends for that security at whatever price the ceiling or floor is set. There is no reopening auction, no continued price discovery, no relief valve. The pressure just builds overnight.

Any market maker trying to manage an intraday position in a stock that hits the band is, for practical purposes, stuck. That structural asymmetry is what makes the NGX mechanism categorically different from what is practised in New York or London, and it is why the instinct to revisit it is correct.

The 100,000-share minimum threshold before a price can move is, in plain terms, a friction tax on price discovery. It means that a buyer and a seller can agree on a new price for a security, execute a trade, and the exchange’s system will refuse to reflect that agreement in the quoted price until the cumulative volume crosses six figures.

The information is real. The transaction happened. But the market is not allowed to know about it yet. In a market where certain names trade only a few thousand shares on a quiet day, this threshold is not a high bar. It is a wall.

The global standard does not work this way. On the NYSE, the standard tick size for most listed stocks is one cent, meaning the price of a stock can move in increments of one cent per share.

There is no minimum volume requirement attached to that movement. A single trade of one share, executed at a new price, moves the last traded price immediately. The market knows. The LSE operates similarly, with tick sizes that vary with price level and by type of stock, calibrated to reflect the economics of each security’s liquidity profile, but again with no volume gate preventing a genuine transaction from being reflected in the price record.

The logic behind the NGX threshold was presumably protective, a desire to prevent thin, low-volume prints from whipsawing quoted prices and misleading investors. That concern is not entirely unreasonable. But the cure is worse than the disease.

What it actually does is create a market where prices are sticky in the wrong direction, where a well-informed seller cannot register their view on a stock without assembling an entire army of shares behind them, and where the price on the screen is not the price of the last trade but the price of the last sufficiently large trade. For a foreign institutional investor trained to trust the tape, this is deeply unsettling.

The combined effect of these two rules is a market where price cannot move intraday beyond 10% in either direction, and where prices below that ceiling are artificially sticky because individual trades cannot move them regardless of content. That is not a market. That is an approximation of a market, operating under rules designed for a different era.

The case for removing both constraints is intuitive. What replaces them matters enormously, and the sequencing matters almost as much. The hard daily cap should be replaced with dynamic VWAP-anchored intraday bands, similar in design to the LULD mechanism in the US, where the reference price updates continuously and orders placed too aggressively outside the band are queued rather than executed.

This preserves genuine price discovery while dampening the kind of disorderly moves that would otherwise invite panic. The 100,000-share volume threshold should be replaced with nothing, which is to say the price of the last trade, any trade, should be the price of record immediately. That is what the tape means in every serious market in the world.

There is a sequencing point here that deserves emphasis. Removing the price band without building the VWAP infrastructure first is a mistake. Removing both constraints without simultaneously reforming the market making framework, including access to equity repo for designated market makers, is also a mistake.

A market maker holding an intraday position in an uncapped market, unable to hedge because no equity repo facility exists, is not a market maker. They are a speculator with obligations and no toolkit. The repo market conversation is not a separate discussion from the price formation one. It is a prerequisite for it.