When the shorts are running the market there is a spread of $3 - $5 between the top exchanges, with BTC-e usually on the bottom of the spread. For the past few days there is almost no spread at all. Bitstamp is $1 below Bitfinex & BTC-e, but that’s it. Coinbase is actually $1 above those two at this time.
How high up can XBT go? Perhaps $280, perhaps more. There may be a quick snap up in next few weeks.
Note: No spreadsheets or graphs were abused to create this report!