Historical share price at exact day and time
On 2012/05/18 at 15:34:00 UTC (11:34:00 EDT) FB was in chaos mode.  The most recent public US trade at that moment was at $40.94, but in the next one second (i.e. before the clock hit 15:34:01) there were several dozen trades as low as $40.76 and as high as $41.00. On 2012/05/30 at 17:21:00 UTC (13:21:00 EDT) the most recent public US trade for FB was at $28.28. You'd have to buy that information. Quoting from this page, Commercial Historical Data Higher resolution and more complete datasets are generally not available for free. Below is a list of vendors which have passed our quality screening (in total, we screened over a dozen vendors). To qualify, the vendor must aggregate data from all US national/regional exchanges as only complete datasets are suitable for research use. The last point is especially important as there are many vendors who just get data from a couple sources and is missing important information such as dark pool trades. They offer some alternatives for free data: Daily Resolution Data 1) Yahoo! Finance– Daily resolution data, with split/dividend adjustments can be downloaded from here. The download procedure can be automated using this tool. Note, Yahoo quite frequently has errors in its database and does not contain data for delisted symbols. 2) QuantQuote Free Data– QuantQuote offers free daily resolution data for the S&P500 at this web page under the Free Data tab. The data accounts for symbol changes, splits, and dividends, and is largely free of the errors found in the Yahoo data. Note, only 500 symbols are available unlike Yahoo which provides all listed symbols. And they list recommendations about who to buy the data from. An alternative to paying thousands of dollars for historical prices by the minute:  Subscribe to real time data for as low as USD$1.5/month from your broker, then browse the chart.
"Though you're looking to repeat this review with multiple securities and events at different times, I've taken liberty in assuming you are not looking to conduct backtests with hundreds of events.  I've answered below assuming it's an ad hoc review for a single event pertaining to one security. Had the event occurred more recently, your full-service broker could often get it for you for free.  Even some discount brokers will offer it so.  If the stock and its options were actively traded, you can request ""time and sales,"" or ""TNS,"" data for the dates you have in mind.  If not active, then request ""time and quotes,"" or ""TNQ"" data. If the event happened long ago, as seems to be the case, then your choices become much more limited and possibly costly.  Below are some suggestions: Wall Street Journal and Investors' Business Daily print copies have daily stock options trading data.  They are best for trading data on actively traded options.  Since the event sounds like it was a major one for the company, it may have been actively traded that day and hence reported in the papers' listings.  Some of the print pages have been digitized; otherwise you'll need to review the archived printed copies. Bloomberg has these data and access to them will depend on whether the account you use has that particular subscription.  I've used it to get detailed equity trading data on defunct and delisted companies on specific dates and times and for and futures trading data.  If you don't have personal access to Bloomberg, as many do not, you can try to request access from a public, commercial or business school library. The stock options exchanges sell their data; some strictly to resellers and others to anyone willing to pay.  If you know which exchange(s) the options traded on, you can contact the exchange's market data services department and request TNS and / or TNQ data and a list of resellers, as the resellers may be cheaper for single queries." James Roth provides a partial solution good for stock picking but let's speed up process a bit, already calculated historical standard deviations: Ibbotson, very good collection of research papers here, examples below Books FreeStockCharts.com keeps some intra-day trading history.  You have to create an account to look up individual stocks.  Once you create a free account you can get intra-day trading history for the last month (Hourly for past month, 15 minutes for past week, 1 minute for past day).  Going back past one month and it only keeps daily close history. Here is Family Dollary's (FDO) hourly intra-day chart for the past month: The difference is that Yahoo is showing the unadjusted price that the security traded for on that date, while google is adjusting for price splits. This means that Google is showing how much you would have had to pay to get what is now one share. Since 1979, JNJ has split 3-for-1 once, and 2-for-1 four times. 3x2x2x2x2 = 48. If you bought 1 share at that time, you would now have 48 shares today. Yahoo is showing a price of $66 for what was then 1 share. $66/48 = 1.375, which Google rounds to 1.38. You can see this if you get the prices from May 14-21, 1981. The stock split 3-for-1, and the price dropped from 108 to 36.38. Yahoo's adjusted close column has not been accurate since they re-wrote the Finance website. It now just represents the closing price. The other relevant field on Yahoo is the Adj. Close. This adjusts for splits, but also adjusts for dividends. Hence why this doesn't match either the Google or Yahoo numbers. In order to see whether you can buy or sell some given quantity of a stock at the current bid price, you need a counterparty (a buyer) who is willing to buy the number of stocks you are wishing to offload. To see whether such a counterparty exists, you can look at the stock's order book, or level two feed. The order book shows all the people who have placed buy or sell orders, the price they are willing to pay, and the quantity they demand at that price. Here is the order book from earlier this morning for the British pharmaceutical company, GlaxoSmithKline PLC.  Let's start by looking at the left-hand blue part of the book, beneath the yellow strip. This is called the Buy side. The book is sorted with the highest price at the top, because this is the best price that a seller can presently obtain. If several buyers bid at the same price, then the oldest entry on the book takes precedence. You can see we have five buyers each willing to pay 1543.0 p (that's 1543 British pence, or £15.43) per share. Therefore the current bid price for this instrument is 1543.0. The first buyer wants 175 shares, the next, 300, and so on. The total volume that is demanded at 1543.0p is 2435 shares. This information is summarized on the yellow strip: 5 buyers, total volume of 2435, at 1543.0. These are all buyers who want to buy right now and the exchange will make the trade happen immediately if you put in a sell order for 1543.0 p or less. If you want to sell 2435 shares or fewer, you are good to go. The important thing to note is that once you sell these bidders a total of 2435 shares, then their orders are fulfilled and they will be removed from the order book. At this point, the next bidder is promoted up the book; but his price is 1542.5, 0.5 p lower than before. Absent any further changes to the order book, the bid price will decrease to 1542.5 p. This makes sense because you are selling a lot of shares so you'd expect the market price to be depressed. This information will be disseminated to the level one feed and the level one graph of the stock price will be updated. Thus if you have more than 2435 shares to sell, you cannot expect to execute your order at the bid price in one go. Of course, the more shares you are trying to get rid of, the further down the buy side you will have to go. In reality for a highly liquid stock as this, the order book receives many amendments per second and it is unlikely that your trade would make much difference. On the right hand side of the display you can see the recent trades: these are the times the trades were done (or notified to the exchange), the price of the trade, the volume and the trade type (AT means automatic trade).  GlaxoSmithKline is a highly liquid stock with many willing buyers and sellers. But some stocks are less liquid. In order to enable traders to find a counterparty at short notice, exchanges often require less liquid stocks to have market makers. A market maker places buy and sell orders simultaneously, with a spread between the two prices so that they can profit from each transaction. For instance Diurnal Group PLC has had no trades today and no quotes. It has a more complicated order book, enabling both ordinary buyers and sellers to list if they wish, but market makers are separated out at the top. Here you can see that three market makers are providing liquidity on this stock, Peel Hunt (PEEL), Numis (NUMS) and Winterflood (WINS). They have a very unpalatable spread of over 5% between their bid and offer prices. Further in each case the sum total that they are willing to trade is 3000 shares. If you have more than three thousand Dirunal Group shares to sell, you would have to wait for the market makers to come back with a new quote after you'd sold the first 3000. The correct p/e for bp.l is 5.80. Bp.l is on the London stock exchange and prices are in local currency. The share price of 493 is reported in pence (not dollars). The EPS is reported in pounds. Using .85 pounds = 85 pence, you calculate the EPS as follows: 493.40/85 = 5.80 PE Yahoo totally screwed up. They converted the .85 pounds into US dollars ($1.34) but didn't convert the 493 pence. By using the 493 as dollars, they got 493.9/1.34 = 368 pe! Notice that Yahoo reports the American Depository Shares (symbol 'BP') with an EPS of $8.06. That correctly reflects that there are 6 shares of BP.l per ADS (1.34 * 6 = 8.04). But why is the share price listed at $46.69? Well...  493 GBp (pence) = 4.93 pounds 4.93 pounds  = 7.73 USD 7.73 USD * 6 shares per ADS = 46.38 USD Interactive Brokers provides historical intraday data including Bid, Ask, Last Trade and Volume for the majority of stocks. You can chart the data, download it to Excel or use it in your own application through their API.  EDIT: Compared to other solutions (like FreeStockCharts.com for instance), Interactive Brokers provides not only historic intraday LAST**** trades **but also historic BID and ASK data, which is very useful information if you want to design your own trading system.  I have enclosed a screenshot to the chart parameter window and a link to the API description. You have to look at the real price of the share to calculate the value of the spread. 42$ at the start, 46$ at the end.  Think of it this way: When price was 42$ the call 45$ was out of the money, worth 100$ of time value only=100 the call 40$ was in the money and worth 200$ of intrinsic + 100 time value=300 the difference was 200$ Now that price is 46$ the call 45$ is worth 100$ in the money, real or intrinsic value the call 40$ is worth 600$ in the money, real or intrinsic value the difference is 500$ NOTE: 1. Commission fees are not included. 2. Time value of 100$ on both calls when price is 42$ is incorrect and for teaching purpose only. For stock splits, let's say stock XYZ closed at 100 on February 5.  Then on February 6, it undergoes a 2-for-1 split and closes the day at 51.  In Yahoo's historical prices for XYZ, you will see that it closed at 51 on Feb 6, but all of the closing prices for the previous days will be divided by 2.  So for Feb 5, it will say the closing price was 50 instead of 100. For dividends, let's say stock ABC closed at 200 on December 18.  Then on December 19, the stock increases in price by $2 but it pays out a $1 dividend.  In Yahoo's historical prices for XYZ, you will see that it closed at 200 on Dec 18 and 201 on Dec 19.  Yahoo adjusts the closing price for Dec 19 to factor in the dividend. "What most of these answers here seem to be missing is that a stock ""price"" is not exactly what we typically expect a price to be--for example, when we go in to the supermarket and see that the price of a gallon of milk is $2.00, we know that when we go to the cash register that is exactly how much we will pay.  This is not, however, the case for stocks. For stocks, when most people talk about the price or quote, they are really referring to the last price at which that stock traded--which unlike for a gallon of milk at the supermarket, is no guarantee of what the next stock price will be.  Relatively speaking, most stocks are extremely liquid, so they will react to any information which the ""market"" believes has a bearing on the value of their underlying asset almost (if not) immediately.  As an extreme example, if allegations of accounting fraud for a particular company whose stock is trading at $40 come out mid-session, there will not be a gradual decline in the price ($40 -> $39.99 -> $39.97, etc.)-- instead, the price will jump from $40 to say, $20.  In the time between the the $40 trade and the $20 trade, even though we may say the price of the stock was $40, that quote was actually a terrible estimate of the stock's current (post-fraud announcement) price. Considering that the ""price"" of a stock typically does not remain constant even in the span of a few seconds to a few minutes, it should not be hard to believe that this price will not remain constant over the 17.5 hour period from the previous day's close to the current day's open.  Don't forget that as Americans go to bed, the Asian markets are just opening, and by the time US markets have opened, it is already past 2PM in London.  In addition to the information (and therefore new knowledge) gained from these foreign markets' movements, macro factors can also play an important part in a security's price-- perhaps the ECB makes a morning statement that is interpreted as negative news for the markets or a foreign government before the US markets open.  Stock prices on the NYSE, NASDAQ, etc. won't be able to react until 9:30, but the $40 price of the last trade of a broad market ETF at 4PM yesterday probably isn't looking so hot at 6:30 this morning... don't forget either that most individual stocks are correlated with the movement of the broader market, so even news that is not specific to a given security will in all likelihood still have an impact on that security's price. The above are only a few of many examples of things that can impact a stock's valuation between close and open: all sorts of geopolitical events, announcements from large, multi-national companies, macroeconomic stats such as unemployment rates, etc. announced in foreign countries can all play a role in affecting a security's price overnight. As an aside, one of the answers mentioned after hours trading as a reason--in actuality this typically has very little (if any) impact on the next day's prices and is often referred to as ""amateur hour"", due to the fact that trading during this time typically consists of small-time investors.  Prices in AH are very poor predictors of a stock's price at open." If you use Google Finance, you will get incorrect results because Google Finance does not show the dividend history. Since your requirement is that dividends are re-invested, you should use Yahoo Finance instead, downloading the historical 'adjusted' price. It does sometimes open one day the same as it closed the previous day.  Take a look at ESCA, it closed October 29th at 4.50, at opened November 1st at 4.50.  It's more likely to change prices overnight than it is between two successive ticks during the day, because a lot more time passes, in which news can come out, and in which people can reevaluate the stock. TdAmeritrade offers this service for free using 3rd party company markit. From markit's site, below is their guarantee.  http://www.markit.com/product/markit-on-demand Markit On Demand delivers an average of two million alerts per day   through various technology platforms and via multiple channels,   including email, instant messages, wireless, RSS and Facebook.   Investors can subscribe to their alerts of choice, and Markit On   Demand guarantees that they will receive an alert within five minutes   of the event trigger for all price and volume alerts The point of that question is to test if the user can connect shares and stock price.  However, that being said yeah, you're right. Probably gives off the impression that it's a bit elementary. I'll look into changing it asap. "The ""price"" is the price of the last transaction that actually took place. According to Motley Fool wiki: A stock price is determined by what was last paid for it. During market hours (usually weekdays from 9:30AM-4:00PM eastern), a heavily traded issue will see its price change several times per second. A stock's price is, for many purposes, considered unchanged outside of market hours. Roughly speaking, a transaction is executed when an offer to buy matches an offer to sell. These offers are listed in the Order Book for a stock (Example: GOOG at Yahoo Finance).  This is actively updated during trading hours. This lists all the currently active buy (""bid"") and sell (""ask"") orders for a stock, and looks like this:  You'll notice that the stock price (again, the last sale price) will (usually*) be between the highest bid and the lowest ask price. * Exception: When all the buy or sell prices have moved down or up, but no trades have executed yet."