Are Multi Exchange Listed equities open to arbitrage trading bc, well they are multiple exchanges?
What keeps the price so similar between the two listings? Is it bc of the chance of arbitrage people snag up any gaps between them ?
Yes to both. However if the stock is listed on 2 exchanges across different jurisdictions, the arbitrage opportunity reduces unless there is an agreed clearing mechanism to transfer the shares.
For example one cannot buy a stock in one exchange and sell it in other. It has to be sold on same exchange. However if you are holding a stock in one exchange, you can sell the position on that exchange and buy same quantity on different exchange at cheaper price. Ofcourse it also means you have money to bridge the funding gap.
If the stock in listed in same jurisdiction, say NYSE vs Nasdaq; or there is a clearing mechanism agreed between the exchanges; i.e. allow to inter-operate then one can buy on one exchange and sell on other.