The Competition Commission has lodged a formal complaint with the Competition Tribunal against the Johannesburg Stock Exchange (JSE), accusing it of abusing its dominant position and blocking fair competition in South Africa’s equity trading market.

In a 101-page referral filed in Pretoria in October, the Commission alleges that the JSE has used its control of the country’s core trading infrastructure to exclude and disadvantage rival platforms such as A2X Markets. The complaint centres on the JSE’s mandatory use of its Broker Dealer Accounting (BDA) System, which all brokers are required touse to trade and clear transactions on the exchange.

According to the Commission, the JSE has refused to make this system interoperable with A2X’s clearing framework, forcing brokers who operate on both exchanges to maintain duplicate and costly systems. This has, in effect, raised operational barriers to entry, disincentivised cross-platform trading, and entrenched the JSE’s market dominance.

The referral accuses the JSE of imposing: “onerous and inefficient” processes on brokers, including restrictions on the Matched Principal Trade (MPT) mechanism, which governs how trades are cleared across different platforms. It also claims the JSE has deliberately refused to combine off-book and on-book trades from A2X into a single settlement instruction, a move that undermines A2X’s competitiveness and liquidity.

The Commission’s investigation, supported by detailed affidavits and trading data, argues that these practices have constrained A2X’s growth since at least 2017, keeping it from achieving its financial break-even point. Charts included in the evidence show a steep decline in A2X trade volumes after 2020, only recovering partially after limited rule adjustments in mid-2022.

In its filing, the Commission requests the Tribunal to declare the JSE’s conduct a contravention of the Competition Act, to order immediate rule changes ensuring full interoperability between exchanges, and to impose an administrative penalty of up to 10% of the JSE’s annual South African turnover.

The case marks one of the most significant competition challenges in the history of South Africa’s capital markets. If upheld, it could force the JSE to open its systems to rivals and reshape the way equity trading is conducted in the country. The JSE has yet to respond publicly, but analysts say the outcome will have far-reaching consequences for the future of financial-market competition in South Africa.