Hong Kong Exchanges and Clearing is racing against the clock to make a formal bid for the London Stock Exchange Group by Wednesday’s deadline after the LSE has indicated a substantial uplift to the preliminary ￡32bn proposal and its terms is needed to unlock further discussions.

The Hong Kong group has undertaken a  three-week charm offensive with LSE shareholders and regulators to persuade them of the merits of its preliminary stock-and-cash proposal worth ￡83.61 a share. But LSE shareholders have been unwilling to back its approach without a formal bid that addresses a range of issues including governance, said two people involved in the discussions.

HKEX has attempted to win investor support after its unsolicited approach was rejected by the LSE, which is pursuing a $27bn deal to buy data and trading group Refinitiv. It has until 5pm Wednesday to make a bid, possibly revising the terms of its initial proposal, or walk away for at least six months unless it can get the LSE to the negotiating table.