Harmony Gold Mining Company is listed on the NYSE and JSE at different prices?
The quotes on JSE are for 100 share lots.  The quotes on NYSE are for single shares.  That still leaves some price difference, but much less than you calculated. (EDIT: Equivalently, the price is quoted in 1/100th of a Rand.  The Reuter's listing makes this explicit since the price is listed as ZAc rather than ZAR.  http://www.reuters.com/finance/stocks/overview?symbol=HARJ.J) As noted in the other answer currently up, NYSE is quoting American Depositary Receipts (ADRs) for this company, which is not directly its stock.  The ADR in this case, if you check the prospectus, is currently 1 share of the ADR = 1 share of the stock on its home market.  A US institution (in this case it looks like BNY Mellon) is holding shares of stock to back each ADR. Arbitrage is possible and does happen.  It's not perfect though, because there are a variety of other cost and risk factors that need to be considered.  There's a good review here: Report by JP Morgan Some summary points: On NYSE it isn't the equity which is listed but is an ADR(American Depositary Receipt). Source A negotiable certificate issued by a U.S. bank representing a specified number of shares (or one share) in a foreign stock that is traded on a U.S. exchange. ADRs are denominated in U.S. dollars, with the underlying security held by a U.S. financial institution overseas. ADRs help to reduce administration and duty costs that would otherwise be levied on each transaction. Else people would make a killing on the arbitrage opportunity. Frankly speaking arbitrage opportunities are more or less non existent. They occur for maybe seconds or milliseconds and the HFT firms and banks trade on it to remove the arbitrage.
Depending on what currency the price is quoted in and is originally sold, currency fluctuation can also carry over onto the price in your currency. An example for that would be bitcoin prices which sometimes show heavy ups and downs in one currency, but seem totally stable in another and can be tracked back to changed exchange rates between currencies. Also like others have said, prices on stocks are not actually fixed. You can offer to buy or sell at any price. Only if 2 people want to buy or sell for the same price there will actually be a transaction. They could have different quotes as there are more than a few pieces here.  Are you talking a Real Time Level II quote or just a delayed quote?  Delayed quotes could vary as different companies would be using different time points in their data.  You aren't specifying exactly what kind of quote from which system are you using here. The key to this question is how much of a pinpoint answer do you want and how prepared are you to pay for that kind of access to the automated trades happening?  Remember that there could well be more than a few trades happening each millisecond and thus latency is something to be very careful here, regardless of the exchange as long as we are talking about first-world stock exchanges where there are various automated systems being used for trading. Different market makers is just a possible piece of the equation here.  One could have the same market maker but if the timings are different,e.g. if one quote is at 2:30:30 and the other is at 2:30:29 there could be a difference given all the trades processed within that second, thus the question is how well can you get that split second total view of bids and asks for a stock.  You want to get all the outstanding orders which could be a non-trivial task. NUGT and DUST are opposites - DUST is a 'bear' (tracks 3x the inverse) and NUGT is a 'bull' (tracks 3x the actual).  So if NUGT is much higher, sounds like people are betting on Gold (or specifically, on the NYSEARCA Gold Miners Index).   When this Investopedia article was written in July 2016, the volumes were reversed: DUST traded ~18m and NUGT traded ~7m.  Just differences in stock market activity. "At the bottom of Yahoo! Finance's S & P 500 quote Quotes are real-time for NASDAQ, NYSE, and NYSE MKT. See also delay   times for other exchanges. All information provided ""as is"" for   informational purposes only, not intended for trading purposes or   advice. Neither Yahoo! nor any of independent providers is liable for   any informational errors, incompleteness, or delays, or for any   actions taken in reliance on information contained herein. By   accessing the Yahoo! site, you agree not to redistribute the   information found therein. 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I'm not familiar with QQQ, but I'm guessing this is something like IShares Ftse 100 (see description here) Many exchanges trade the same securities.  An order may be posted to a secondary exchange, but if the National Best Bid and Offer data provider malfunctions, only those with data feeds from that exchange will see it. Only the data provider for the primary exchange where a stock is listed provides the NBBO. Missing orders are very common with the NBBO data providers.  NASDAQ's order consolidator has had many failures over the past few years, and the data provider's top executive has recently resigned. Brokers have no control over this system.  A broker may be alerted to a malfunction by an accountholder, but a broker may only inform the relevant exchange and the relevant data provider. Academic research into ADRs seems to suggest that pairs-trading ADRs and their underlying shares reveals that there certainly are arbitrage opportunities, but that in most (but not all cases) such opportunities are quickly taken care of by the market. (See this article for the mexican case, the introduction has a list of other articles you could read on the subject). In some cases parity doesn't seem to be reached, which may have to do with transaction costs, the risk of transacting in a foreign market, as well as administrative & legal concerns that can affect the direct holder of a foreign share but don't impact the ADR holder (since those risks and costs are borne by the institution, which presumably has a better idea of how to manage such risks and costs). It's also worth pointing out that there are almost always arbitrage opportunities that get snapped up quickly: the law of one price doesn't apply for very short time-frames, just that if you're not an expert in that particular domain of the market, it might as well be a law since you won't see the arbitrage opportunities fast enough. That is to say, there are always opportunities for arbitrage with ADRs but chances are YOU won't be able to take advantage of it (In the Mexican case, the price divergence seems to have an average half-life of ~3 days). Some price divergence might be expected: ADR holders shouldn't be expected to know as much about the foreign market as the typical foreign share holder, and that uncertainty may also cause some divergence. There does seem to be some opportunity for arbitrage doing what you suggest in markets where it is not legally possible to short shares, but that likely is the value added from being able to short a share that belongs to a market where you can't do that. Dear Sir/madam We are Local Village Gold Miners from Rep. of Guinea, In West African. I am a Member of the Said Community and in charge of Marketing, Advertising, communication and sourcing potential diamond and gold dust buyers, agents/brokers or partners for our mined gold dust AU./DIAMONDS. Prior To The Latest Privilege Accorded Local Gold and Diamond Miners in Guinea Conakry Since April 2007 to Market and Sell Diamond and Gold Dust AU themselves, Thus my offer to AU Gold Dust and Diamond UNCUT Dust prospective buyers, Brokers, representatives, agents, intermediaries and partners willing To Establish Meaningful Business transaction that is Viable and Durable with us. Hence, I'm offering you a Fresh Gold Dust. AU for sale with the following specifications and details. COMMODITY.......................................AURUM UTALIUM (AU) Form................................Gold Dust/nugget Powder. Quantity..........................123kg - 500kgs and more. Quality/Purity.................. 22 carat or better. Finesse..........................92% OR Better. Location.......................... Conakry Origin............................. Guinea . Price per kg......................$35,000 USD/KG  AS FOR THE DIAMOND THAT IS UNCUT, WE ARE IN POSITIONS OF OVER 4850 Carats OF GAMS STONE OF FDGH AND LM GRADES. We are looking forward to your response if our product does interest you. Accept our warm hearted Regards: NB : this is my alternative       CONTACT US CAN SPEAK ENGLISH ,FRENCH AND CHINESE Tel:+22467118646 webs www.africalocalgoldminers.webs.com E-mail: africalocalgoldminers@yahoo.com Rue DI 519 Conakry Republique de Guinee  Best Regard Mr john dabo I found the answer. It was the Stock Ticker that I was looking for. So, if I understand correctly the price at certain moment is the price of the latest sale and can be used to get a global picture of what certain stock is worth at that certain instant. Assuming the data you're referring to is this line: the difference might be related to the different exchanges on which the stock trades.  FINRA could be listing the reported volume from one exchange, while the NASDAQ data might be listing the volume on all exchanges. This is an important distinction because AAV is a Canadian company that is listed on the Toronto Stock Exchange and the NYSE. The Q at the end of the line stands for NASDAQ, according to FINRA's codebook for those data. My guess is that the FINRA data is only reporting the volume for the NASDAQ exchange and not the total volume for all exchanges (Toronto, NASDAQ, NYSE, etc.) while the data straight from NASDAQ, oddly enough, is reporting the total volume. However, FINRA could also face reporting discrepancies, since it's a regulatory body and therefore might not have the most up-to-date volume data that the various exchanges can access.  I don't know if it's related or not, but looking at the NASDAQ historical data, it looks like the volume on March 6, the day you're asking about, was much lower than the volume in most of the days immediately before or after it. For all I know, something might have happened that day concerning that particular stock or the market as a whole. I don't remember anything in particular, but you never know. Yes, the ADR will trade on a separate exchange from the underlying one, and can (and does) see fluctuations in price that do not match the (exchange corrected) fluctuations that occur in the original market. You are probably exposing yourself to additional risk that is related to: 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. They don't have to track each other, it could just be listed on more than one exchange.  The price on one exchange does not have to match or track the price on the other exchange. This is actually quite common, as many companies are listed on two or more exchanges around the world. "You might consider learning how the ""matching"" or ""pairing"" system in the market operates.  The actual exchange only happens when both a buyer and a seller overlap their respect quotes.   Sometimes orders ""go to market"" for a particular volume.  Eg get me 10,000 Microsoft shares now.  which means that the price starts at the current lowest seller, and works up the price list until the volume is met.  Like all market it trades, it has it's advantages, and it's dangers.  If you are confident Microsoft is going to bull, you want those shares now, confident you'll recoup the cost.  Where if you put in a priced order, you might get only none or some shares. Same as when you sell.  If you see the price (which is the price of the last completed ""successful"" trade.  and think ""I'm going to sell 1000 shares"". then you give the order to the market (or broker), and then the same as what happened as before.  the highest bidder gets as much as they asked for, if there's still shares left over, they go to the next bidder, and so on down the price... and the last completed ""successful"" trade is when your last sale is made at the lowest price of your batch. If you're selling, and selling 100,000 shares. And the highest bidder wants 1,000,000 shares you'll only see the price drop to that guys bid.  Why will it drop (off the quoted price?).  Because the quoted price is the LAST sale, clearly if there's someone still with an open bid on the market...then either he wants more shares than were available (the price stays same), or his bid wasn't as high as the last bid (so when you sale goes through, it will be at the price he's offering).   Which is why being able to see the price queues is important on large traders. It is also why it can be important put stops and limits on your trades, een through you can still get gapped if you're unlucky.  However putting prices (""Open Orders"" vs ""(at)Market Orders"") can mean that you're sitting there waiting for a bounce/spike while the action is all going on without you). safer but not as much gain (maybe ;) ) that's the excitement of the market, for every option there's advantages...and risks... (eg missing out) There are also issues with stock movement, shadowing, and stop hunting, which can influence the price. But the stuff in the long paragraphs is the technical reasons." http://mobile.nytimes.com/blogs/economix/2014/04/02/the-many-classes-of-google-stock/ Are you counting both class A and other share classes?