Stock Exchange in US
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.
You pointed out that HFT does not create ipods are mine minerals.  Neither does human trading. HFT is a proxy for human trading.  Although the computer is executing trades automatically based on an algorithm, it is still using money from a human being's account so the trading is still being done with someone's money. Fast execution of trades is desirable in exchanges.  Imagine two exchanges:  One only executes trades once a month, the other executes trades once a week.  Which exchange would be more desirable?  The exchange that trades once a week.  Why?  Because if I'm holding a stock that I would like to sell, I want to sell it now - not a month from now.  Same reason for buying.  This concept works all the way down to seconds and fractions of seconds. The issue with HFT, however, is there are cases where the market goes against the HFT algorithm and the algorithm continues to execute trades driving prices up or down by large amounts in the matter of minutes or even seconds. The exchange frequently cancels these trades which only encourages more aggressive HFT trading since HFT traders can have their losses cancelled.  This is a privilege that LFTs (low frequency traders) do not receive.  This is a valid criticism of HFTs. A short list of such cancelled trades: 8/26/2010: Nasdaq cancels trades of CORE stock 10/4/2010: Nasdaq cancels trades of CENX stock 10/15/2010: NYSE cancels trades of PAY stock 10/18/2010: NYSE cancels $500 million worth of SPY trades 5/18/2011: NYSE cancels 15,900 trades of BEE.PR.C 6/21/2011: Nasdaq cancels CNTY trades 12/2/2011: London Metals Exchange cancel trades of copper If I buy VUSA from one exchange, can I sell it in a different exchange, assuming my brokerage account lets me trade in both exchanges? Or is it somehow tied to the exchange I bought it from? This doesn't happen for all securities and between all stock exchanges. So that is dependent on broker and country. I checked for VUSA with Selftrade. They categorically refused allowing me to trade in VUSA in different exchanges. I can only buy and sell in same currency only, albeit sell(buy) in the same exchange where I buy(sell) from. Should be the same behaviour for all brokers for us mere mortals, if you are a bank or a millionaire than that might be a different question.  The VUSA you quote is quoted in GBP in LSE and in EUR in AEX, and the ETF has been created by an Irish entity and has an Irish ISIN.  As Chris mentioned below, happens between US and Canadian exchanges, but not sure it happens across all exchanges. You cannot deal in inter-listed stocks in LSE and NYSE. Since it's the same asset, its value should not vary across exchanges once you compensate for exchange rates, right? Yes, else it opens up itself for arbitrage (profit without any risk) which everybody wants. So even if any such instance occurs, either people will exploit it to make the arbitrage profit zero (security reflects the equilibrium price) or the profit from such transaction is so less, compared with the effort involved, that people will tend to ignore it. Anyways arbitrage profit is very difficult to garner nowadays, considering the super computers at work in the market who exploit these discrepancies, the moment they see them and bring the security right to the zero arbitrage profit point. If there's no currency risk because of #2, what other factors should I consider when choosing an exchange to trade in? Liquidity? Something else? Time difference, by the time you wake up to trade in Japan, the Japanese markets would have closed. Tax implications across multiple continents. Law of the land, providing protection to investors. Finding a broker dealing in markets you want to explore or dealing with multiple brokers. Regulatory headaches. "Depends. The short answer is yes; HSBC, for instance, based in New York, is listed on both the LSE and NYSE. Toyota's listed on the TSE and NYSE. There are many ways to do this; both of the above examples are the result of a corporation owning a subsidiary in a foreign country by the same name (a holding company), which sells its own stock on the local market. The home corporation owns the majority holdings of the subsidiary, and issues its own stock on its ""home country's"" exchange. It is also possible for the same company to list shares of the same ""pool"" of stock on two different exchanges (the foreign exchange usually lists the stock in the corporation's home currency and the share prices are near-identical), or for a company to sell different portions of itself on different exchanges. However, these are much rarer; for tax liability and other cost purposes it's usually easier to keep American monies in America and Japanese monies in Japan by setting up two ""copies"" of yourself with one owning the other, and move money around between companies as necessary. Shares of one issue of one company's stock, on one exchange, are the same price regardless of where in the world you place a buy order from. However, that doesn't necessarily mean you'll pay the same actual value of currency for the stock. First off, you buy the stock in the listed currency, which means buying dollars (or Yen or Euros or GBP) with both a fluctuating exchange rate between currencies and a broker's fee (one of those cost savings that make it a good idea to charter subsidiaries; could you imagine millions a day in car sales moving from American dealers to Toyota of Japan, converted from USD to Yen, with a FOREX commission to be paid?). Second, you'll pay the stock broker a commission, and he may charge different rates for different exchanges that are cheaper or more costly for him to do business in (he might need a trader on the floor at each exchange or contract with a foreign broker for a cut of the commission)." Cross-listing shouldn't be an issue, as the sole reason stocks would behave differently on different exchanges would be due to exchange rates (sure, noise and time differences, but weekly data should take care most of that). If you're using MSCI World index figures in USD, you either have to convert stocks denominated in other currencies to USD at their historical fx rates, or just save a lot of time and use data from stocks listed in the US, when available. Try Google Finance Screener ; you will be able to filter for NASDAQ and NYSE exchanges. $38 was the IPO price. This was price per share for those investors who bought directly from the underwriters (Morgan Stanley, etc.)  $42.06 was the first secondary market price, the price at which two private parties first exchanged the shares on an exchange, in this case NASDAQ. "Some history: In the US, this is very tightly controlled and regulated. Although stock market securities insider trading is a relatively new crime around the world (20-30 year old), the United States  is exceptional for offering the longest sentences for it, although it is still far more lucrative than and carries lower sentences than something like petty larceny. The perception of illegal insider trading has changed in the US over the years, although it is based on much older fraud statutes the regulators and the courts have only really developed modern case law against insider trading in the past 20-30 years. The US relies on its vast network of registered broker-dealers to detect and report abnormal trading activity and the regulator (SEC) can quickly obtain emergency court orders from rent-a-judges (Administrative Law Judges) to freeze trader's assets to prevent them from withdrawing, or quickly enacting sanctions. So this reality helps deter trading on material inside information. So for someone that needs to get an information advantage on the market, it is [simply] necessary for them to rationalize how this information could be inferred from public sources.  Similarly there is a thin line between non-public information and public information, the ""lab experiment"" example would be material insider information, but the fact that there will be litigation over a company's key patents may be ""public"" as soon as the lawyer submits the complaint to the court system. It is also worth noting that there are A LOT of financial products trading in the capital markets, and illegal insider trading laws only applies to trading of shares of a company. So if a major holder in gold is about to liquidate all their holdings, being short gold futures is not subject to civil and criminal sanctions. Hope this helps. The above examples should help you understand what kind of information is material inside information and what kind is not, and how it is relevant to trading decisions." The total value of the stock market more or less tracks the total value of the companies listed in the stock market, which is more or less the total value of the US economy (since very few industries are nationalized or dominated by privately held companies). The US economy has consistently grown over time, thanks to the wonders of industrialization, the discovery of new markets, new natural resources, etc.  Thus, the stock market has continued to grow as well. Will it forever?  No.  The United States will not exist for ever.  But there's no obvious reason it won't continue to grow, at least for a while, though of course if I could accurately predict that I would be far richer than I am. Why do other countries not have the same result?  China is its own ball of wax since it's a sort-of-market-sort-of-command economy.  Japan has major issues economically right now and doesn't really have the natural or people resources; it also had a huge market bubble a while back that it's never recovered from. And many European countries are doing fine.  German's DAX30 index was at around 2500 in 2004 and is now at nearly 13000.  That's pretty fast growth. If you go back further (there was a crash ending in around 2004), you can see around the fall of the Berlin wall it was still around 2000; even going that far back, that's about an 8% annual bump.  The FTSE was also around 2000 back then, around 8000 now, which is around 5% annual growth.   Many of these indexes were more seriously hurt than the US markets in the two major crashes of this millenium; while the US markets fell a lot in 2008, they didn't fall nearly as much as many smaller markets in 2002, so had less to recover from.  Both DAX and FTSE suffered similar falls in 2002 to 2008, and so even though during good periods they've grown quite quickly, they haven't overall done as well as they could have given the crashes.