Symbologies on different markets are complicated by history and independence and always result in some company symbols varying between exchanges. Historically the lack of standardisation was due to a lack of communication (the exchanges are competing businesses after all) and lack of foresight. How could the exchanges know that companies would become more and more multinational and list on many more exchanges than existed at the time when it still takes a month for goods to travel between countries? The symbol for each company on each exchange was chosen to fit their name and, in some cases, their business and was chosen without any thought to other exchanges' symbologies. This naturally lead to different companies on different exchanges having the same symbol which, in turn, resulted in these companies needing different symbols if and when they listed on other markets. A further complication is that when companies merge or otherwise change their name they change ticker but their old ticker needs to be maintained for historical data purposes; it is necessary to be able to identify a company that no longer exists. This backward compatibility issue means that even more symbols are unusable in the exchange ticker universe.
There have been many attempts to standardise the symbologies including ISINs (which are widely used outside of North America) and CUSIPs for bonds but these have had some difficulty in being accepted and adopted as they don't match up with any part of the business name and are a significant change over the exchange symbols. For example ISINs are 12 characters long where as symbols are typically three to four characters long so are more recognisable, smaller, and easier to store when you are dealing with about 300,000 trades per day.
On a personal note the lack of standardisation makes my job incredibly difficult; I on board markets for my clients amongst other tasks and the varying symbologies can be amazingly complicated.
Pricing between exchanges for the same (or equivalent) instrument should in theory always match due to arbitrage. The key reasons why they don't are related to currency, systemic risk, and cost differences.
Arbitrage is the act of buying the same item on one market where it is under priced compared with another market and selling it on the other market. This will, of course, cause the prices to converge. The problem is, however, that the two markets are never as ideal as that; different markets charge different amounts to trade so arbitraging between two exchanges even in the same country may not be profitable as the charges will eat away the available risk free profits. In this case the more expensive market to trade on will lag against the less expensive market and volumes will be higher on the latter so it will also be more liquid.
When the exchanges are in different countries or have more significant differences the problem is compounded. If one country or exchange is seen to be less credit worthy for political or economic (usually debt) reasons there is a higher risk that the trade on that exchange will fail in some way and you will lose all of your money. Countries have even gone as far as seizing control of all of the money in the stock exchange in the past or banning foreign entities from trading and seizing their assets in the country. Each country and exchange has its own credit rating and risk of failure or political and economic instability and a lower credit rating or a higher risk (which we call systemic risk) will result in traders requiring a higher risk premium to trade in that country. This leads to prices on markets in that country being higher to offset the increased risk.
The final cause of deviation in prices is thanks to foreign exchange. The exchanges you list cover three different currencies; CHF, EUR and SEK. Clearly the absolute prices in these different currencies will differ but even when converted into the same currency (we normally use USD) the prices will vary. This is due to exchange rate risk. Some currencies, such as SEK, are less widely traded meaning that there is a bigger risk that volatility will move the FX rate heavily against you whilst you are engaging in arbitrage. You are not only engaging in stock price arbitrage but also in FX arbitrage at the same time which is far more complicated and likely to cause price disparities based on FX risk.
A final thought, which is unlikely to be true here, is that different exchanges in different countries close at different times. If one of the exchanges above happened to close an hour before the others the closing price would be an hour out of date compared to the others. An hour is a very long time on the markets and could move the price more than 1%, particularly in closing auctions and especially if there is news on the company or sector in that hour. Note that I didn't check the market closes so this is unlikely to be the case for your example but would be between, say, US markets and European ones and many stocks are dual listed between the US and Europe.
