RE:RE:RE:NYSE vs. Toronto exchange Market makers, at least for OTC stocks, are generally international banking entities that engage in cross-border transactions, having customers in Canada and the US. They can buy on the TSX and the put the stocks in inventory and then sell them off the NYSE/NASDAQ exchanges on the OTC to American customers.
Back in the day, the Big Board had "specialists" who dealt with a handful of stocks and they were the ones responsible maintaining liquidity in the markets. They had to have a high enough capitalization before the exchange would give them the rights to be the specialists for an individual stock. Each stock I believe only had one specialist. They maintained the books (buy/sell) and therefore had inside information which allowed them their profit margins on trading in the stocks. Of course, this was back in the day when the NYSE stocks traded in 1/8 of a dollar increments. Nowadays, we have fractional cents trading and everything is on the decimal system. With the advent of rampant electronic trading, it is possible that the NYSE has become more decentralized with the specialists being replaced by a handful of market makers, similar to what you find on the OTC. I do so little trading in NYSE stocks I haven't kept up with them for years. The outside of the NYSE on Wall Street looks as impressive as ever, but inside it is mostly empty with very few floor traders.
All this being said, I am glad that WRN is dual listed and trading on the NYSE since that alleviates the fees that TDA or Schwab would otherwise charge me for WRN trades.