As roeal_v pointed out this deal requires that that transaction not go through. And again, Revinitiv is being purchased for only 4X earnings (which are themselves 3X the LSE's).

Fundamentally though I don't see why an exchange is worth much. Yes it sees all the deal flow, but it can sell info, it can't trade on it (else, apart from getting in trouble with regulators, it would lose all its customers).

Exchanges can have something that looks like Monopoly power when you need access to their data. Yes, certain instruments trade everywhere and on different exchanges, but when LSE/NYM/ICE etc is considered THE benchmark for XYZ contract, you have to buy their feed to get the best pricing data.

Whys Refinitiv so cheap?

That's a pretty good multiple for their sector.

"The proposed 31.6 billion pounds cash-and-share transaction would only go ahead if the LSE’s takeover of Refinitiv does not proceed, HKEX said."