FCA opens probe into London Stock Exchange rooftop access for high-speed links

The Financial Conduct Authority has opened a probe into access to the rooftop of the London Stock Exchange's data-centre building amid concerns that the building's owner has prevented other trading groups from installing radio equipment used for high-speed market connectivity.

City regulators say only the London Stock Exchange Group, which operates the exchange, has been able to use the rooftop for radio equipment, blocking alternatives for firms that rely on sub-millisecond links for market data and order transmission. The FCA said it had provisionally accepted a proposal from LSEG and the landlord of the building to share rooftop access, but has not reached a decision on whether competition law has been breached.

The regulator's inquiry focuses on whether the access arrangements gave LSEG an unfair advantage by denying competing trading firms the physical ability to install microwave or millimetre-wave radio links on the roof. Such links are used by some market participants to shave microseconds off the time it takes to receive price feeds and send orders, an advantage in certain types of electronic trading.

An FCA spokeswoman said the authority was investigating the arrangements and assessing whether they raised competition concerns. The FCA's provisional acceptance of a sharing proposal signals that it is exploring remedial solutions while its review continues, but the spokeswoman stressed that no final determination had been made.

A spokesman for LSEG said the company had not been the subject of any infringement decision and confirmed discussions with the landlord about enabling broader rooftop access. He declined to provide further detail on the terms of the proposal while talks were ongoing.

Industry participants said rooftop access to city buildings has become a focal point for disputes in several markets where firms invest in low-latency infrastructure. Physical access, spectrum licensing and landlord permissions can all affect whether a firm can deploy short-hop radio links. Market operators and data-centre owners often control rooftop and mast space that competitors need for those connections.

The regulator's probe comes amid wider scrutiny of market infrastructure and fairness in access to trading venues and data. Regulators in other jurisdictions have previously examined the allocation of colocation facilities, data feeds and connection services after concerns that preferential arrangements could disadvantage some market participants.

Trade associations and some trading firms have argued that open and non-discriminatory access to essential facilities, such as rooftops and fibre exchanges, is important to maintain fair competition, particularly where physical constraints limit alternatives. Landlords and infrastructure owners have countered that security, safety and technical constraints can justify controlled access and that shared arrangements can mitigate exclusionary effects.

The FCA has not named any specific trading firms that sought rooftop access, nor disclosed the exact technical or contractual barriers they faced. The regulator's review will examine whether contractual terms, property rights or other arrangements improperly restricted competitors and whether any remedial measures are required to restore effective competition.

Market participants said any formal finding that competition law had been breached could lead to mandated sharing arrangements, changes to lease terms, or other measures to ensure non-discriminatory access. Such outcomes could have implications for the economics of low-latency trading and for data-centre landlords that host critical market infrastructure.

The FCA's probe is ongoing. The regulator did not set out a timetable for concluding the investigation. LSEG and the landlord said they were engaged in discussions with the FCA and other parties to seek a resolution.