RE: Hmm20 Jan 2021 15:52
They do not need to be the same price. Theoretically, on a dual-listed company the valuations of both listings should match on the fundamentals, as long as the voting rights, dividend rights etc are the same, because each share is exposed to the same risk and reward of the business.
But part of the share price is on sentiment. And you cannot convert a TILS share to a TLSA share except by buying and selling on the open market, which means finding a seller and buyer to be the other side of the transaction (via the MMs).
If people sell TILS to buy TLSA en masse, because of the notion that they should be the same, then this would actually cause the price to diverge, as lots of TILS sellers will drive the price down, while lots of TLSA buyers will drive the price up.
If the direction reverses and people sell their TLSA to buy TILS in aggregate, then TLSA will drop and TILS will rise. But the price of both are also affected by buyers and sellers who don't care about trying to arbitrage this.