Is there a way to tell how many stocks have been shorted?
Generally the number of shares of a U.S. exchange-listed stock which have been shorted are tracked by the exchange and reported monthly.  This number is usually known as the open short interest.  You may also see a short interest ratio, which is the short interest divided by the average daily volume for the stock. The short interest is available on some general stock data sites, such as Yahoo Finance (under Key Statistics) and dailyfinance.com (also on a Key Statistics subpage for the stock).
Patrick Byrne (CEO of Overstock.com) ran a somewhat interesting website awhile back called 'Deep Capture' which focused heavily on naked short selling and bear raids. He was called all sorts of names and many 'serious' journalist types brushed his allegations off.   His basic argument was that a cabal of hedge funds would simultaneously naked short a specific equity and then a coordinated group of journalists and message board jockeys would disparage the company as loudly and publicly as possible, driving the price down. Naked shorting is supposed to be illegal since you can hold the types of positions like in the linked article about Citigroup where the number of shares sold short actually exceeds the number of shares in existence.  The group he named was essentially a who's who of hedge funds and fraudsters and included many names of prominent politically active 'reformed' criminals from the S&amp;L days on Wall St. I can't remember how the cards fell, but the scheme allegedly involved Michael Milliken, Sam Antar (from Crazy Eddie's Fraud), Gary Weiss, Jim Cramer, etc etc.   It was a fascinating story.   Byrne actually followed through with several lawsuits (one of which was settled after a Rocker Partners paid Byrne $5 million dollars to settle).   The 'Deep Capture' site is down, but I [found a decent article](http://www.theregister.co.uk/2008/10/01/wikipedia_and_naked_shorting/print.html) that sums up some of the shenanigans, including a journalist sock-puppeting to edit Wikipedia, repeatedly denying it, being IP-traced to inside the DTCC building (the Wall St. entity responsible for clearing trades, including naked shorts). "You can see all the (millions) of trades per day for a US stock only if you purchase that data from the individual exchanges (NYSE, NASDAQ, ARCA, ...), from a commercial market data aggregator (Bloomberg, Axioma, ...), or from the Consolidated Tape Association.  In none of that data will you ever find identifying information for the traders. What you are recalling regarding the names of ""people from the company"" trading company stock is related to SEC regulations stating that people with significant ownership of company stock and/or controlling positions on the company board of directors must publicize (most of) their trades in that stock.  That information can usually be found on the company's investor relations website, or through the SEC website." "Yes these are the number of shareholders that are not held in ""street name"" plus the different brokerages that hold the shares in ""street name"".  So the stat is pointless since it really only lists the few people who own the stocks outside of a brokerage account and a bunch of wall street brokers." "Yes, you could sell what you have and bet against others that the stock price will continue to fall within a period of time ""Shorting"".  If you're right, your value goes UP even though the stock price goes down. This is a pretty darn risky bet to make.  If you're wrong, there's no limit to how much money you can owe.  At least with stocks they can only fall to zero!  When you short, and the price goes up and up and up (before the deadline) you owe it! And just as with stocks, someone else has to agree to take the bet.  If a stock is pretty obviously tanking, its unlikely that someone would oppose your bet. (It's probably pretty clear that I barely know what I'm talking about, but I was surprised not to see this listed among the answers.)" The day trader in the article was engaging in short selling.  Short selling is a technique used to profit when a stock goes down.  The investor borrows shares of a stock from someone else and sells them.  After the stock price goes down, the investor buys the shares back and returns them, pocketing the difference. As the day trader in the article found out, it is a dangerous practice, because there is no limit to the amount of money you can lose. The stock was trading at $2, and the day trader thought the stock was going to go down to $1.  He borrowed and sold 8,400 shares at $2.  He hoped to buy them back at $1 and earn $8,400 profit.  Instead, the stock went up a lot, and he was forced to buy back the shares at $18.50 per share, or about $155,400.  He had had $37,000 with E-Trade, which they took, and he is now over $100,000 in debt. You can calculate the fully diluted shares by comparing EPS vs diluted (adjusted) EPS as reported in 10K. I don't believe they report the number directly, but it is a trivial math exercise to reach it. The do report outstanding common stock (basis for EPS). "Thanks for the response.   I am using WRDS database and we are currently filtering through various variables like operating income, free cash flow etc.  Main issue right now is that the database seems to only go up to 2015...is there a similar database that has 2016 info?  filtering out the ""recent equity issuance or M&amp;A activity exceeding 10% of total assets"" is another story, namely, how can I identify M&amp;A activity? I suppose we can filter it with algorithm stating if company's equity suddenly jumps 10% or more, it get's flagged" No, but insider information would have tipped them off on the timings of when to time some of their actions... possibly planning shorting it ahead, all kinds of who-diggery that those financial wizards can do to make shit tons of money off stocks / companies losing money. Simple Schwaab does not have actually your securities they have leased them out and have to borrow them back. all assets are linked with derivatives now. They show on the balance sheet but have to be untangled. Thats why the market drops disproportionally fast to the actual number of shares sold. The Art of Short Selling by Kathryn Stanley providers for many case studies about what kind of opportunities to look for from a fundamental analysis perspective. Typically things you can look for are financing terms that are not very favorable (expensive interest payments) as well as other constrictions on cash flow, arbitrary decisions by management (poor management), and dilution that doesn't make sense (usually another product of poor management). From a quantitative analysis perspective, you can gain insight by looking at the credit default swap rate history, if the company is listed in that market. The things that affect a CDS spread are different than what immediately affects share prices. Some market participants trade DOOMs over Credit Default Swaps, when they are betting on a company's insolvency. But looking at large trades in the options market isn't indicative of anything on its own, but you can use that information to help confirm your opinion. You can certainly jump on a trend using bad headlines, but typically by the time it is headline news, the majority of the downward move in the share price has already happened, or the stock opened lower because the news came outside of market hours. You have to factor in the short interest of the company, if the short interest is high then it will be very easy to squeeze the shorts resulting in a rally of share prices, the opposite of what you want. A short squeeze doesn't change the fundamental or quantitative reasons you wanted to short. The technical analysis should only be used to help you decide your entry and exit price ranges amongst an otherwise random walk. The technical rules you created sound like something a very basic program or stock screener might be able to follow, but it doesn't tell you anything, you will have to do research in the company's public filings yourself. You can use Google Finance Stock Screener for screening US stocks. Apparently it doesn't have the specific criterion (Last Price % diff from 52 week low) you are (were!) looking for.  I believe using its api you can get it, although it won't exactly be a very direct solution. "The shares available to short are a portion of those shares held by the longs. This number is actually much easier to determine outside of active trading hours, but either way doesn't really impact the matter at hand since computers are pretty good at counting things. If your broker is putting up obstacles to your issuing sell short limit orders in the pre-market then there is likely some other reason (maybe they reserve that function to ""premium"" account holders?)" For a company listed on NASDAQ, the numbers are published on NASDAQ's site. The most recent settlement date was 4/30/2013, and you can see that it lists 27.5 million shares as held short.  NASDAQ gets these numbers from FINRA member firms, which are required to submit them to the exchange twice a month: Each FINRA member firm is required to report its “total” short interest positions in all customer and proprietary accounts in NASDAQ-listed securities twice a month. These reports are used to calculate short interest in NASDAQ stocks. FINRA member firms are required to report their short positions as of settlement on (1) the 15th of each month, or the preceding business day if the 15th is not a business day, and (2) as of settlement on the last business day of the month.* The reports must be filed by the second business day after the reporting settlement date. FINRA compiles the short interest data and provides it for publication on the 8th business day after the reporting settlement date. &gt; A short position also loses money if the stock just appreciates more slowly than the broader market, which is one way an overvaluation can correct itself.  Is there a derivative based on the literal second derivative (acceleration) of the stock price? If so, you'd be able to short those, yes? Reuters has a service you can subscribe to that will give you lots of Financial information that is not readily available in common feeds.  One of the things you can find is the listing/delist dates of stocks.  There are tools to build custom reports.  That would be a report you could write.  You can probably get the data for free through their rss feeds and on their website, but the custom reports is a paid feature. FWIW re-listing(listings that have been delisted but return to a status that they can be listed again) is pretty rare.  And I can not think of too many(any actually) penny stocks that have grown to be listed on a major exchange.