It will mark the second overseas acquisitions of the HKEX after it took over the London Metal Exchange in 2012 to step into commodities, according to South China Morning Post.
In a statement posted on HKEX website, Chief Executive Charles Li said 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," he said.
"A combined group will be strongly placed to benefit from the dynamic and evolving macroeconomic landscape while enhancing the long-term resilience and relevance of London and Hong Kong as global financial centres," said Li.
According to CNN, the announcement comes hot on the heels of the LSE's 27 billion dollar deal to acquire financial data company Refinitiv. That deal is aimed at transforming the LSE into global markets and information juggernaut to rival Michael Bloomberg's financial data empire.
In a statement, the LSE described the offer as "unsolicited, preliminary and highly conditional."
"The board will consider this proposal and will make a further announcement in due course," it said, adding that it remains committed to its proposed acquisition of Refinitiv and expected to write to shareholders seeking their approval for that deal in November.