Well there is a time difference so you cant compare the close in Toronto to the close in Oslo. I dont know what the time difference is but I do know that in England it is 5 hours difference from Toronto. So assuming the time difference is about the same in Oslo as it is in england and if both exchanges closed at 4PM their time Oslo would be closing at 11 am toronto time . Make sense?. Als I cant remember the actual term used but when the VSE was a separate entitity from TSE some traders would play both markets on interlisted stocks. So if a stock was 1.00 to 1.01in Toronto and .98 to .99 in Vancouver some traders just bot at .99 in Vancouver and at the same time sold at 1.00 in Toronto. Some traders made all their money on the market doing that. It was about as guaranteed a win as you can get in the stock market. If you were sharp and could do that 10 20 or 30 times in a day was better than stealing.Arbitrage. That is the term for doing that.