How can I find data on delisted stocks?
You need a source of delisted historical data. Such data is typically only available from paid sources. According to my records, AULT (Ault Inc) began as an OTC stock in the 1980s prior it having an official NASDAQ listing.  It was delisted on 27 Jan 2006.  Its final traded price was $2.94.  It was taken over at a price of $2.90 per share by SL Industries. Source: Symbol AULT-200601 within Premium Data US delisted stocks historical price data set available from http://www.premiumdata.net/products/premiumdata/ushistorical.php Disclosure: I am a co-owner of Norgate / Premium Data. In general you cannot. Once the security is no longer listed on the exchange - it doesn't have to provide information to the exchange and regulators (unless it wants to be re-listed). That's one of the reasons companies go private - to keep their (financial and other) information private. If it was listed in 1999, and is no longer listed now - you can dig through SEC archives for the information. You can try and reach out to the company's investors' relations contact and see if they can help you with the specific information you're looking for.
None-fanboy source [here](http://tech.fortune.cnn.com/2011/12/05/top-android-phone-maker-faces-u-s-import-ban-tuesday/).  Links to the two patents here: ['647 - System and method for performing an action on a structure in computer-generated data](http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&amp;Sect2=HITOFF&amp;d=PALL&amp;p=1&amp;u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&amp;r=1&amp;f=G&amp;l=50&amp;s1=5,946,647.PN.&amp;OS=PN/5,946,647&amp;RS=PN/5,946,647) ['263 - Real-time signal processing system for serially transmitted data ](http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&amp;Sect2=HITOFF&amp;d=PALL&amp;p=1&amp;u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&amp;r=1&amp;f=G&amp;l=50&amp;s1=6,343,263.PN.&amp;OS=PN/6,343,263&amp;RS=PN/6,343,263)  I don't believe '647 will be a real threat because the language it uses means the patent is extremely broad and describes something that is fundamental to the operation of practically every web browser, indexing software and electronic guide on the planet.  Like Samsung's (I think) attempt to injunct the iPhone using its 3G patents, the ITC will likely rule that the technology/system is too critical to modern function and hence cannot be a valid reason for injunction.  '263, however, is a real problem for Android.  My interpretation of the patent is that it's claiming a system where the OS parses data from a wirelessly transmitted stream based on type and offers it to other apps instead of having apps actively request data from the OS.  As I understand it, this is exactly how Android's intent-activity model works.  Because this model of data sharing is at the core of Android and fundamental to its design, it's practically impossible to circumvent without completely rewriting Android, which would break everything.  Furthermore, because there is a clear alternative on how to share data (ie. apps request from OS, OS gives data parsed from stream), the protection used against the 3G injunction attempt against Apple cannot be used here.  Simply put, the ITC can easily put an injunction on HTC on the basis of '263, and if it does, then *all* Android phones can expect to receive similar injunctions very very quickly after that.  It would be nice to see what /r/business thinks any possible injunction may have not only on the stocks of the smartphone companies but also on the entire smartphone market as a whole.  Personally, I think any injunction based on either patent will make the stocks of any Android makers and Google plummet.  It would probably chill the mobile market for a while as investors try to guess just what other patents Apple might be able to use against the remaining platforms of Blackberry and Windows Phone 7.  And then things will probably return to normal, sans Android and the companies that strongly supported it like Samsung, HTC and Motorola.  Samsung and Moto will probably the worst hit, while HTC will end up focusing on WinPhone 7.    Thoughts? Since then I had gotten a job at a supermarket stocking shelves, but recently got fired because I kept zoning out at work This is not a good sign for day trading, where you spend all day monitoring investments.  If you start focusing on the interesting math problem and ignoring your portfolio, you can easily lose money.  Not so big a problem for missed buy opportunities, but this could be fatal for missed sale opportunities.  Realize that in day trading, if you miss the uptick, you can get caught in a stock that is now going down.   And I agree with those who say that you aren't capitalized well enough to get started.  You need significantly more capital so that you can buy a diversified portfolio (diversification is your limitation, not hedging).  Let's say that you make money on two out of three stocks on average.  What are the chances that you will lose money on three stocks in a row?  One in twenty-seven.  What if that happens on your first three stocks?   What if your odds at starting are really one in three to make money?  Then you'll lose money more than half the time on each of your first three stocks.  The odds don't favor you.   If you really think that finance would interest you, consider signing up for an internship at an investment management firm or hedge fund.  Rather than being the person who monitors stocks for changes, you would be the person doing mathematical analysis on stock information.  Focusing on the math problem over other things is then what you are supposed to be doing.  If you are good at that, you should be able to turn that into a permanent job.  If not, then go back to school somewhere.  You may not like your schooling options, but they may be better than your work options at this time.   Note that most internships will be easier to get if you imply that you are only taking a break from schooling.  Avoid outright lying, but saying things like needing to find the right fit should work.  You may even want to start applying to schools now.  Then you can truthfully say that you are involved in the application process.  Be open about your interest in the mathematics of finance.  Serious math minds can be difficult to find at those firms.   Given your finances, it is not practical to become a day trader.  If you want proof, pick a stock that is less than $100.  Found it?  Write down its current price and the date and time.  You just bought that stock.  Now sell it for a profit.  Ignore historical data.  Just monitor the current price.  Missed the uptick?  Too bad.  That's reality.  Once you've sold it, pick another stock that you can afford.  Don't forget to mark your price down for the trading commission.  A quick search suggests that $7 a trade is a cheap price.  Realize that you make two trades on each stock (buy and sell), so that's $14 that you need to make on every stock.  Keep doing that until you've run out of money.  Realize that that is what you are proposing to do.   If you can make enough money doing that to replace a minimum wage job, then we're all wrong.  Borrow a $100 from your mom and go to town.  But as others have said, it is far more realistic to do this with a starting stake of $100,000 where you can invest in multiple stocks at once and spread your $7 trading fee over a hundred shares.  Starting with $100, you are more likely to run out of money within ten stocks. If you want to combine old/new thoughts then maybe look af psychological or general theory of reflexivity.  One of the underlying assumptions in big data and AI is that if you have enough data, you will have the truth. but then look at elections in the US and UK or the fact that no one can predict exchanges rates because the market reacts in a dobbel loop.  how about some good old self-driving German cars as a subject? Lots of political, ethical, R&amp;D, management and tech considerations are in that area, finde ich. Viel Spass damit :) "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." "Real-time equity (or any other market) data is not available for free anywhere in the US.  It is always delayed by 10-15 minutes. On the other hand, online brokers who target the ""day trader"" (Interactive Brokers, TD Ameritrade, etc.) offer much closer to real-time data AND feature all the tools/alerts/charts/etc. you could ever possibly dream of.  I bet the type of alert you're asking for is available with just a couple of clicks on one of these brokers' platforms. Of course, accounts with these online brokers are not free; you must pay for these sophisticated tools and fast market access.  Another down side is that the data feeds sent to you by even the most sophisticated online broker are still delayed by tens of seconds compared to the data feeds used by big banks and professional investors.  Not to mention that the investment arm of the broker you use will be making its own trades based on the data feeds before relaying them on to you. So this begs the question: why do you need real-time information?  Are you trying to ""day trade"" -- i.e. profit from minute-to-minute fluctuations in the stock market?  (I can't in good conscience recommend that, but best of luck to you.)  If on the other hand you don't truly need ""real-time"" data for your application, then I support @ChrisDegnen's approach -- use public data feeds and write your own software.  You probably will not find any free tools for the sort of alerting you're looking for because most folks who want these types of alerts also need faster feeds and are therefore already using an online broker's tools." Yes, http://shares.telegraph.co.uk/stockscreener/ has what you're looking for. Yahoo Finance's Historical Prices section allows you to look up  daily historical quotes for any given stock symbol, you don't have to hit a library for this information. Your can choose a desired time frame for your query, and the dataset will include High/Low/Close/Volume numbers. You can then download a CSV version of this report and perform additional analysis in a spreadsheet of your choice. Below is Twitter report from IPO through yesterday: http://finance.yahoo.com/q/hp?s=TWTR&a=10&b=7&c=2013&d=08&e=23&f=2014&g=d Just look at the filing date of the 10Q and then Yahoo the closing price or Google it. I assume you are looking for market reactions to SEC filings?   If you want to look at the closing stock price for the end of the period which the filing covers, it's like on the first page of the filing when the period (either quarterly or yearly) ends. This data is generally less useful, however, because it really is just another day in the market for the company. The actual release of the data to the public is more important.