Did the New York Stock Exchange ever close on a weekday so they could file paperwork?
Yes, from June 1968 until December 1968, they closed the NYSE every Wednesday so they could catch up on paperwork representing billions of dollars in unprocessed transactions.  Even after the NYSE re-opened on Wednesdays in January 1969, they still had to close it early at 2pm for seven more months. Forbes has a description of this: Not to be forgotten, though, is the Paperwork Crunch. In a day of email and the Cloud and trading completed in microseconds, the idea that Wall Street needed Wednesdays off in the late 1960′s to catch up on back-office tasks seems especially quaint. Yet, in 1968, the NYSE found itself sitting on more than $4 billion in unprocessed transactions. Trading had risen to 21 million shares daily; by contrast, even in the heavy volume days in 1929, trading never went above 16 million shares. Papers stacked on desks. A (now old) joke formed: If a fan blew the wrong way in a Wall Street office, visitors below could expect a ticker-tape parade. “Everybody agreed that the securities-processing system had virtually broken down, and the only major point of dispute was who was more responsible for the mess: the back offices of the brokerage firms of the stock-transfer agents,” Securities and Exchange Commission Commissioner Ray Garrett, Jr. said in 1974. Some 100 broker-dealers failed, crumbling under the pressure of fulfilling those back-orders. The fix: an organization akin to the FDIC, the Securities Investor Protection Corporation. Wall Street would stick to the shortened weeks from June to December; in January, Wednesday trading resumed, though it ended early at 2 for another seven months.
Try Google Finance Screener ; you will be able to filter for NASDAQ and NYSE exchanges. the financial information is generally filed via SEDAR (Canada) or SEC (US) before the conference call with the investment community.  This can take before either before the market opens or after the market closes.  The information is generally distribute to the various newswire service and company website at the same time the filing is made with SEDAR/SEC. I don't quite understand the NYSE argument that the credit system helps NASDAQ undercut NYSE on pricing and force brokers to trade on NASDAQ. I thought if you were trading a stock listed on NASDAQ, you traded through them and if you were trading a stock listed on NYSE, you'd trade over there. The choice of exchange coming down to the stocks you want to trade more than anything. Are the exchanges also acting as endpoints on trades for securities listed on the other exchange? You can find the NYSE holiday dates listed on the exchange's own site (already linked in answer above), which should obviously be consulted as the most reliable source; they are also published in an article that I have written here: NYSE Holidays 2016, which provides additional information about traditions and events that can be expected to lead to unscheduled closures, and closed dates for holidays that are day-of-month rather than date specific (e.g. President's Day and Memorial Day). NYSE Holidays are not quite identical to those for the Chicago Mercantile Exchange, though most US stock exchange dates are the same. Also, note that both the Merc (via the Globex platform) and NYSE Arca have different normal cash sessions and trading hours to the New York Stock Exchange. The NYSE holidays are listed online here: https://www.nyse.com/markets/hours-calendars I work in Reserves management at a Central Bank. We work more or less the same hours...but the content of the day is very different. Trading is usually wrapped up by 11-12pm. Then I have a ton a time in the afternoon to hit up the gym, attend economist presentations, grab a lunch, or grab beer with colleagues. Generally very relaxed....very against the industry A stock's price does not move in a completely continuous fashion.  It moves in discrete steps depending on who is buying/selling at given prices. I'm guessing that by opening bell the price for buying/selling a particular stock has changed based on information obtained overnight. A company's stock closes at $40.  Overnight, news breaks that the company's top selling product has a massive defect.  The next morning the market opens.  Are there any buyers of the stock at $40?  Probably not.  The first trade of the stock takes place at $30 and is thus, not the same as the previous day's close. It turns out that in this special case for New York, they have a law that says that if you are changing your filing status from resident to nonresident, you must use the accrual method for calculating capital gains. So in this case, the date on the papers is the important one. "Company values (and thus stock prices) rely on a much larger time frame than ""a weekend"".  First, markets are not efficient enough to know what a companies sales were over the past 2-3 days (many companies do not even know that for several weeks).  They look at performance over quarters and years to determine the ""value"" of a company.  They also look forward, not backwards to determine value.  Prior performance only gives a hint of what future performance may be.  If a company shut its doors over a weekend and did no sales, it still would have value based on its future ability to earn profits." 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. During a circuit breaker, no trading occurs. These policies have been implemented to maintain exchange liquidity since the NYSE nearly went bankrupt during the 1987 crash because many members had become insolvent. If an order is filled before the halt, it will stand unless busted.  During the Flash Crash, many orders were busted. "There is more than one exchange where stock can be traded.   For example, there is the New York Stock Exchange and the London Stock Exchange.  In fact, if you look at all the exchanges, there is essentially continuous trading 24/7 for many financial instruments (eg US government bonds). The closing price quoted in papers is usually the price at the close on the NYSE.  However, options close after that and so there is after-the-close trading in many stocks with active options, so the price at the close of options trading at CBOE is often used. The ""real"" price is always changing.  But for the purpose of discussion, using the closing price in NYSE (for NYSE listed stocks) is pretty standard and unlikely to be questioned.  Likewise, using Bloomberg's price makes sense. Using some after-hours or small market quote could lead to differences with commonly accepted numbers - until tomorrow :)" "The difficulty is that you are thinking of a day as a natural unit of time.  For some securities the inventory decisions are less than a minute, for others, it can be months.  You could ask a similar question of ""why would a dealer hold cash?"" They are profit maximizing firms and, subject to a chosen risk level, will accept deals that are sufficiently profitable.  Consider a stock that averages 1,000 shares per day, but for which there is an order for 10,000 shares.  At a sufficient discount, the dealer would be crazy not to carry the order.   You are also assuming all orders are idiosyncratic.  Dividend reinvestment plans (DRIP) trigger planned purchases on a fixed day, usually by averaging them over a period such as 10 days.  The dealer slowly accumulates a position leading up to the date whenever it appears a good discount is available and fills the DRIP orders out of their own account.  The dealer tries to be careful not to disturb the market leading up to the date and allows the volume request to shift prices upward and then fills them." "For any large company, there's a lot of activity, and if you sell at ""market"" your buy or sell will execute in seconds within a penny or two of the real-time ""market"" price.  I often sell at ""limit"" a few cents above market, and those sell within 20 minutes usually.  For much smaller companies, obviously you are beholden to a buyer also wanting that stock, but those are not on major exchanges.  You never see whose buy order you're selling into, that all happens behind the curtain so to speak." "Yes when I place an order with my broker they send it out to the exchange. - For individual investors, what are some cons and pros of trading on    the exchanges directly versus indirectly via brokers? I may be mistaken(I highly doubt it), but from my understanding you cannot trade directly through an exchange as a retail investor. BATS allows membership but it is only for  Your firm must be a registered broker-dealer, registered with a Self Regulatory Organization (SRO) and connected with a clearing firm. No apple (aapl) is listed on the NASDAQ so trades go through the NASDAQ for aapl. Caterpillar Inc (CAT) is listed on the NYSE so trades go through the NYSE.  The exchange you trade on is dependent on the security, if it is listed on the NYSE then you trade on the NYSE. As a regular investor you will be going through a broker. When looking to purchase a security it is more important to know about the company and less important to know what exchange it is listed on. Since there are rules a company must comply with for it to be listed on certain exchanges, it does make a difference but that is more the case when speaking about a stock listed Over the Counter(OTC) or NYSE. It is not important when asking NYSE or NASDAQ? Selecting a broker is something that's dependent on your needs. You should ask your self, ""whats important to me?"", ""Do I want apps(IE: iPhone, android)?"" ""Do I need fancy trading tools?"". Generally all the brokers you listed will most likely do the trick for you. Some review sites: Brokerage Review  Online Broker Review 2012 Barron's 2012 Online Broker Review"