Stock not available at home country nor at their local market - where should I buy it
"Theoretically, it shouldn't matter which one you use.  Your return should only depend on the stock returns in SGD and the ATS/SGD exchange rate (Austrian Schillings? is this an question from a textbook?).  Whether you do the purchase ""through"" EUR or USD shouldn't matter as the fluctuations in either currency ""cancel"" when you do the two part exchange SGD/XXX then XXX/ATS. Now, in practice, the cost of exchanging currencies might be higher in one currency or the other.  Likely a tiny, tiny amount higher in EUR.  There is some risk as well as you will likely have to exchange the money and then wait a day or two to buy the stock, but the risk should be broadly similar between USD and EUR."
Any large stockbroker will offer trading in US securities. As a foreign national you will be required to register with the US tax authorities (IRS) by completing and filing a W-8BEN form and pay US withholding taxes on any dividend income you receive.  US dividends are paid net of withholding taxes, so you do not need to file a US tax return.  Capital gains are not subject to US taxes.  Also, each year you are holding US securities, you will receive a form from the IRS which you are required to complete and return. You will also be required to complete and file forms for each of the exchanges you wish to received market price data from. Trading will be restricted to US trading hours, which I believe is 6 hours ahead of Denmark for the New York markets.  You will simply submit an order to the desired market using your broker's online trading software or your broker's telephone dealing service. You can expect to pay significantly higher commissions for trading US securities when compared to domestic securities. You will also face potentially large foreign exchange fees when exchaning your funds from EUR to USD. All in all, you will probably be better off using your local market to trade US index or sector ETFs. Check out WorldCap.org. They provide fundamental data for Hong Kong stocks in combination with an iPad app. Disclosure: I am affiliated with WorldCap. I agree that a random page on the internet is not always a good source, but at the same time I will use Google or Yahoo Finance to look up US/EU equities, even though those sites are not authoritative and offer zero guarantees as to the accuracy of their data. In the same vein you could try a website devoted to warrants in your market.  For example, I Googled toronto stock exchange warrants and the very first link took me to a site with all the information you mentioned.  The authoritative source for the information would be the listing exchange, but I've spent five minutes on the TSX website and couldn't find even a fraction of the information about that warrant that I found on the non-authoritative site. I stock is only worth what someone will pay for it.  If you want to sell it you will get market price which is the bid. You seem to think that stock exchanges are much more than they actually are. But it's right there in the name: stock exchange. It's a place where people exchange (i.e. trade) stocks, no more and no less. All it does is enable the trading (and thereby price finding). Supposedly they went into mysterious bankruptcy then what will happen to the listed companies  Absolutely nothing. They may have to use a different exchange if they're planning an IPO or stock buyback, that's all. and to the shareholder's stock who invested in companies that were listed in these markets ?  Absolutley nothing. It still belongs to them. Trades that were in progress at the moment the exchange went down might be problematic, but usually the shutdown would happen in a manner that takes care of it, and ultimately the trade either went through or it didn't (and you still have the money). It might take some time to establish this. Let's suppose I am an investor and I bought stocks from a listed company in NYSE and NYSE went into bankruptcy, even though NYSE is a unique business, meaning it doesn't have to do anything with that firm which I invested in. How would I know the stock price of that firm  Look at a different stock exchange. There are dozens even within the USA, hundreds internationally. and will I lose my purchased stocks ?  Of course not, they will still be listed as yours at your broker. In general, what will happen after that ?  People will use different stock exchanges, and some of them migth get overloaded from the additional volume. Expect some inconveniences but no huge problems. No, you shouldn't buy it. The advice here is to keep any existing holdings but not make new purchases of the stock. There are some brokers in the US who would be happy to open an account for non-US residents, allowing you to trade stocks at NYSE and other US Exchanges. Some of them, along with some facts: DriveWealth Has support in Portuguese Website TD Ameritrade Has support in Portuguese Website Interactive Brokers Account opening is not that straightforward Website One risk not mentioned is that foreign stock might be thinly traded on your local stock market, so you will find it harder to buy and sell, and you will be late to the game if there is some sudden change in the share price in the original country. The easiest route for you to go down will be to consult wikipedia, which will provide a comprehensive list of all US stock exchanges (there are plenty more than the ones you list!). Then visit the websites for those that are of interest to you, where you will find a list of holiday dates along with the trading schedule for specific products and the settlement dates where relevant. In answer to the other part of your question, yes, a stock can trade on multiple exchanges. Typically (unless you instruct otherwise), your broker will route your order to the exchange where it can be matched at the most favorable price to you at that time. The essential difference b/n ADR and a common share is that ADR do not have Voting rights. Common share has.  There are some ADR that would in certain conditions get converted to common stock, but by and large most ADR's would remain ADR's without any voting rights. If you are an individual investor, this difference should not matter as rarely one would hold such a large number of shares to vote on General meeting on various issues. The other difference is that since many countries have regulations on who can buy common shares, for example in India an Non Resident cannot directly buy any share, hence he would buy ADR. Thus ADR would be priced more in the respective market if there is demand. For example Infosys Technologies, an India Company has ADR on NYSE. This is more expensive around 1.5 times the price of the common share available in India (at current exchange rate). Thus if you are able to invest with equal ease in HK (have broker / trading account etc), consider the taxation of the gains in HK as well the tax treatment in US for overseas gains then its recommended that you go for Common Stock in HK. Else it would make sense to buy in US. It doesn't matter which exchange a share was purchased through (or if it was even purchased on an exchange at all--physical share certificates can be bought and sold outside of any exchange). A share is a share, and any share available for purchase in New York is available to be purchased in London. Buying all of a company's stock is not something that can generally be done through the stock market. The practical way to accomplish buying a company out is to purchase a controlling interest, or enough shares to have enough votes to bind the board to a specific course of action. Then vote to sell all outstanding shares to another company at a particular fixed price per share. Market capitalization is an inaccurate measure of the size of a company in the first place, but if you want to quantify it, you can take the number of outstanding shares (anywhere and everywhere) and multiply them by the price on any of the exchanges that sell it. That will give you the market capitalization in the currency that is used by whatever exchange you chose. yes, there does need to be demand. on heavily traded stocks, there is no reason to be concerned. on thinly traded equities, you will want to check the market depth before placing a sell.  the company is likely not the one that is buying your shares on the open market. While most all Canadian brokers allow us access to all the US stocks, the reverse is not true.  But some US brokers DO allow trading on foreign exchanges. (e.g. Interactive Brokers at which I have an account).  You have to look and be prepared to switch brokers.  Americans cannot use Canadian brokers (and vice versa). Trading of shares happens where-ever two people get together - hence the pink sheets.  These work well for Americans who want to buy-sell foreign stocks using USD without the hassle of FX conversions.  You get the same economic exposure as if the actual stock were bought.   But the exchanges are barely policed, and liquidity can dry up, and FX moves are not necessarily arbitraged away by 'the market'.  You don't have the same safety as ADRs because there is no bank holding any stash of 'actual' stocks to backstop those traded on the pink sheets. What I ended up doing was finding where each ticker of Novo was registered (what exchange), then individually looking up the foreign taxation rules of the containing country.  Luckily, most companies only have a few tickers so this wasn't too hard in the end. You might have to pay a premium for the stocks on the dividend tax–free exchanges. For example, HSBC on the NYSE yields 4.71% versus HSBC on the LSE which yields only 4.56%. Assuming the shares are truly identical, the only reason for this (aside from market fluctuations) is if the taxes are more favorable in the UK versus the US, thus increasing demand for HSBC on the LSE, raising the price, and reducing the yield. A difference of 0.15% in yield is pretty insignificant relative to a 30% versus 0% dividend tax. But a key question is, does your country have a foreign tax credit like the US does? If so you (usually) end up getting that 30% back, just delayed until you get your tax return, and the question of which exchange to buy on becomes not so clear cut. If your country doesn't have such a tax credit, then yes, you'll want to buy on an exchange where you won't get hit with the dividend tax. Note that I got this information from a great article I read several months back (site requires free registration to see it all unfortunately). They discuss the case of UN versus UL--both on the NYSE but ADRs for Unilever in the Netherlands and the UK, respectively. The logic is very similar to your situation.