HKEX says the combination would create a leading market infrastructure group with a global footprint and, crucially, close ties to China.

The proposed deal would see the migration of HKEX’s trading and clearing platforms to LSEG’s technology, leading, says HKEX, to a revenue uplift in key businesses from cross-selling and innovation opportunities and a reduction in HKEX’s capital expenditures in connection with existing systems and future investment plans.

HKEX was forced to halt trading only last week, blaming a software bug for disruptions.

The Hong Kong exchange group already has a strong base in London, following the acquisition of the London Metal Exchange in 2012.

In terms of future governance, HKEX says it has begun conversations with certain regulators in the UK and Hong Kong and looks forward to discussing the transaction in detail with LSEG and all relevant regulatory bodies.

Charles Li, chief executive of HKEX, says: “Bringing HKEX and LSEG together will redefine global capital markets for decades to come. Both businesses have great brands, financial strength and proven growth track records. Together, we will connect East and West, be more diversified and we will be able to offer customers greater innovation, risk management and trading opportunities."

HKEX's publication of its offer caught the London Stock Exchange off-guard. The LSE Board - which just last month agreed terms for a $27 billion buyout of Refinitiv - has yet to make statement.

Update A statement issued by the LSEG notes the "unsolicited, preliminary and highly conditional" proposal to acquire the entire share capital of LSEG.

A further announcement will be forthcoming, but the London exchange operator insists that it "remains committed to and continues to make good progress on its proposed acquisition of Refinitiv". A circular is expected to be posted to LSEG shareholders in November 2019 to seek their approval of the transaction.