Is it possible to quantify the probability of sudden big movements for a high-volume stock?
"Certainly no one knows in advance how much a stock is going to swing around. However, there are measures of how much it has swung around in the past, and there are people who will estimate the probability. First of all, there's a measure of an individual stock's volatility, commonly referred to as ""beta"". A stock with a beta of 1 tends to rise and fall about as much as the market at large. A stock with a beta of 2, in the meantime, would rise 10% when the market is up 5%. These are, of course, historical averages. See Wikipedia: http://en.wikipedia.org/wiki/Beta_(finance) Secondly, you can get an implied measure of volatility expectations by looking at options pricing. If a stock is particularly volatile, the chance of a big price move will be baked into the price of the stock options. (Note also that other things affect options pricing, such as the time value of money.) For an options-based measure of the volatility of the whole market, see the Volatility Index aka the ""Fear Gauge"", VIX.  Wikipedia: http://en.wikipedia.org/wiki/VIX Chart: http://finance.yahoo.com/q?s=%5EVIX Looking at individual stocks as a group (and there's an oxymoron for you), individual stocks are definitely much more likely to have big moves than the market. Besides Netflix, consider the BP oil spill, or the Tokyo Electric Power Company's Fukushima incident (yow!). I don't have any detailed statistics on quantitatively how much, mind you, but in application, a standard piece of advice says not to put more than 5% of your portfolio in a single company's stock. Diversification protects you. (Alternatively, if you're trying to play Mr. Sophisticated Stock-Picker instead of just buying an index fund, you can also buy insurance through stock options: hedging your bets. Naturally, this will eat up part of your returns if your pick was a good one)." The P/E is currently 20. In hindsight, it's easy to see that when it was 50, not long ago, it was very overpriced. They were not adding customers or increasing revenue as they should have to sustain that P/E level.  Probability? I suppose this can happen with any company that has both a high P/E and non-diversified business. Why did you think this company was large and stable? Their marketing blunders simply pricked the bubble level pricing these guys had.  (Disclaimer - I am actually a happy customer of Netflix. For $8/mo, I get 6-8 DVDs and neither spend gas nor time to get them. Others who grew used to free streaming feel otherwise) "This is a classic correlation does not imply causation situation.  There are (at least) three issues at play in this question: If you are swing- or day-trading then the first and second issues can definitely affect your trading.  A higher-price, higher-volume stock will have smaller (percentage) volatility fluctuations within a very small period of time. However, in general, and especially when holding any position for any period of time during which unknowns can become known (such as Netflix's customer-loss announcement) it is a mistake to feel ""safe"" based on price alone. When considering longer-term investments (even weeks or months), and if you were to compare penny stocks with blue chip stocks, you still might find more ""stability"" in the higher value stocks.  This is a correlation alone — in other words, a stable, reliable stock probably has a (relatively) high price but a high price does not mean it's reliable. As Joe said, the stock of any company that is exposed to significant risks can drop (or rise) by large amounts suddenly, and it is common for blue-chip stocks to move significantly in a period of months as changes in the market or the company itself manifest themselves. The last thing to remember when you are looking at raw dollar amounts is to remember to look at shares outstanding.  Netflix has a price of $79 to Ford's $12; yet Ford has a larger market cap because there are nearly 4 billion shares compared to Netflix's 52m." "In general, when companies are regarded as ""hot"" growth stocks, they are expected to keep up an accelerated level of growth for a good long time. That accelerated growth justifies a high PE relative to a slow-growth stock. When companies that are supposed to grow miss expectations or (worse) lose money, the markets punish the stock severely... Particularly if the company doesn't make analysts aware of problems early on. Netflix is a great example of a company bungling a few different business problems, creating a much bigger one in the process. A poorly conceived rate hike killed the reliable cash flow of the company, and that crazy Quixter thing just confused everyone. Now nobody trusts the management. BlackBerry is another example of a high performing company that just screwed up, damaging shareholders in the process. We're living in a very challenging era today, but growth stocks are always risky by nature -- growing a company rapidly is very difficult."
ode2k noted the liquidity can very wildly especially 9 months out and there will be little volume even in the largest stocks.  Victor noted standard measures of liquidity don't always apply cleanly to options as they are priced using a hybrid of model and market inputs.  So your question is generally very hard to answer on SE, but you can get an answer yourself without too much trouble. The best way to get a feel for slippage in your case is to just get quotes.  Most systems should let you get a quote for both buying and selling options at the same time.  This will give you a feeling for how much you are paying in spread.  Do the same for near dated options to get a feeling for spread size when you end up selling. You should factor in some widening of spreads at bad times, but this should get you a feeling for the scale of the slippage problem. Yes it is possible but with a caveat.  It is a pattern that can be observed in many lightly traded stocks that usually have a small market cap.  I am talking about a stock that trades less than 2,000 shares per day on average. you can check google scholar for some research reports on it.  depends how complex you want to get...  it is obviously a function of the size of the portfolio of each type of asset. do you have a full breakdown of securities held? you can get historical average volumes during different economic periods, categorized by interest rates for example, and then calculate the days required to liquidate the position, applying a discount on each subsequent day. I've never heard of such a thing, but seems like if such a product existed it would be easily manipulated by the big trading firms - simply bet that trading volume will go up, then furiously buy and sell shares yourself to artificially drive up the volume. The fact that it would be so easily manipulated makes me think that no such product exists, but I could be wrong. You have just answered your question in the last sentence of your question:  More volume just means more people are interested in the stock...i.e supply and demand are matched well. If the stock is illiquid there is more chance of the spread and slippage being larger. Even if the spread is small to start with, once a trade has been transacted, if no new buyers and sellers enter the market near the last transacted price, then you could get a large spread occurring between the bid and ask prices. Here is an example, MDG has a 50 day moving average volume of only 1200 share traded per day (obviously it does not trade every day).  As you can see there is already an 86% spread from the bid price. If a new bid price is entered to match and take out the offer price at $0.039, then this spread would instantly increase to 614% from the bid price. I suggest you look at many stocks' price history, especially around earnings announcements. It's certainly a gamble. But an 8 to 10% move on a surprise earning announcement isn't unheard of. If you look at the current price, the strike price, and the return that you'd get for just exceeding the strike by one dollar, you'll find in some cases a 20 to 1 return. A real gambler would research and find companies that have had many earnings surprises in the past and isolate the options that make the most sense that are due to expire just a few days after the earnings announcement. I don't recommend that anyone actually do this, just suggesting that I understand the strategy. Edit - Apple announced earnings. And, today, in pre-market trading, over an 8% move. The $550 calls closed before the announcement, trading under $2. While trading in stochastic I've understood, one needs reference (SMA/EMA/Bolinger Band and even RSI) to verify trade prior entering it. Stochastic is nothing to do with price or volume it is about speed. Adjusting K% has ability to turn you from Day trader to -> swing trader to -> long term investor. So you adjust your k% according to chart time-frame. Stochastic setup for 1 min, 5 min ,15, 30, 60 min, daily, weekly, monthly, quarterly, half yearly and yearly are all different. If you try hopping from one time-frame to another just because it is below oversold or above overbought region with same K%, you may get confused. Worst you may not square-off your loss making trade. And rather not use excel; charts gives better visual for oscillators. "I am strongly skeptical of this.  In fact, after reading your question, I did the following: I wrote a little program in python that ""simulates"" a stock by flipping a coin. Each time the coin comes up heads, the stock's value grows by 1. Each time the coin comes up tails, the stock's value drops by 1.  I then group, say, 50 of these steps into a ""day"", and for each day I look at opening, closing, maximum and minimum. This is then graphed in a candlestick chart.  Funny enough, those things look exactly like the charts analysts look at. Here are a few examples:    If you want to be a troll, show these to a technical analyst and ask them which of these stocks you should sell short and which of them you should buy. You can try this at home, I posted the code here and it only needs Python with a few extra packages (Numpy and Pylab, should both be in the SciPy package). In reply to a comment from JoeTaxpayer, let me add some more theory to this. My code actually performs a one-dimensional random walk. Now Joe in the comments says that an infinite number of flips should approach the zero line, but that is not exactly correct. In fact, there is a high chance to end up far from the zero line, because the expected distance from the start for a random walk with N steps is sqrt(N).  What does indeed approach the zero line is if you took a bunch of these random walks and then performed the average over those. There is, however, one important aspect in which this random walk differs from the stock market: The random walk can go down as far as it likes, whereas a stock has a bottom below which it cannot fall. Reaching this bottom means the company is bankrupt and gets removed from the market. This means that the total stock market, which we might interpret as a sum of random walks, does indeed have a bias towards upwards movement, since I'm only averaging over those random walks that don't go below a certain threshold. But you can really only benefit from this effect by being broadly diversified." "The price of a company's stock at any given moment is established by a ratio of buyers to sellers.  When the sellers outnumber the buyers at a given price, the stock price drops until there are enough people willing to buy the stock to balance the equation again.  When there are more people wanting to purchase a stock at a given price than people willing to sell it, the stock price rises until there are enough sellers to balance things again.  So given this, it's easy to see that a very large fund (or collection of very large funds) buying or selling could drive the price of a stock in one direction or another (because the sheer number of shares they trade can tip the balance one way or another).   What's important to keep in mind though is that the ratio of buyers to sellers at any given moment is determined by ""market sentiment"" and speculation.  People selling a stock think the price is going down, and people buying it think it's going up; and these beliefs are strongly influenced by news coverage and available information relating to the company.  So in the case of your company in the example that would be expected to triple in value in the next year; if everyone agreed that this was correct then the stock would triple almost instantly.  The only reason the stock doesn't reach this value instantly is that the market is split between people thinking this is going to happen and people who think it won't.   Over time, news coverage and new information will cause one side to appear more correct than the other and the balance will shift to drive the price up or down.  All this is to say that YES, large funds and their movements CAN influence a stock's trading value; BUT their movements are based upon the same news, information, analysis and sentiment as the rest of the market.  Meaning that the price of a stock is much more closely tied to news and available information than day to day trading volumes.  In short, buying good companies at good prices is just as ""good"" as it's ever been.   Also keep in mind that the fact that YOU can buy and sell stocks without having a huge impact on price is an ADVANTAGE that you have.  By slipping in or out at the right times in major market movements you can do things that a massive investment fund simply cannot." "There's an old adage in the equities business - ""buy on rumor, sell on fact"".  Sometimes the strategy is to buy as soon as the rumor is out about a potential merger and then sell off into the news when it is actually announced, since this is normally when the biggest bounce occurs as part of a merger. The other part of the analysis you should do is to understand which of the companies benefits most (or is hurt the worst) by the merger and then make your play accordingly.  Sometimes the company being acquired will see a bounce while the acquiring firm takes a hit, which is an indication the experts think the acquisition will be a drag on the acquiring company (perhaps because it is taking on a great deal of debt to make the acquisition, or because the acquiring firm is paying too much of a premium for what it's getting in return).  Other times the exact opposite is true, where the company being acquired takes a hit while the buyer bounces, and again, the reasons for this can vary widely. If you wait until the merger is actually announced then by the time you get in, most of the premium from the announcement will likely have already been realized, and you'll be buying near the top of the market for the stock.  The key is to be ahead of the other sellers by seeing the opportunities before they do and then knowing when to get out before everyone else does.  Not an easy thing to pull off when you're trying to anticipate the markets, but it can be done if you do the right research and have patience. Good luck!" You should not look at volume in isolation but look at it together with other indicators and/or the release of news (good or bad). When there is lower than average volume this could be an indication that the stock is in a bit of a holding pattern, possibly waiting for some company or economic news to come out (especially when accompanied by small changes in price). It could also mean that trading in a certain direction is drying up and the trend is about to end (this could be accompanied with a large move in price). When there is higher than average volume (2 to 3 times more or higher), this could be due to the release of company results, company or economic news, or the start or end of a trend (especially if accompanied by a gap). A large increase in volume accompanied by a large fall in price (usually a gap down) may also be an indication the stock has gone ex-dividend. There could be a range of reasons for variations in volume to the average volume. That is why you need to look at other indicators, company reporting and news, and economic news in combination with the volume changes to get a grasp of what is really happening. It is a fool's errand to attribute abnormal option volume or volatility to any meaningful move in the stock. One side of the chain is frequently more expensive than the other. The relationship between historical volatility and implied volatility is dubious at best, and also a big area of study. The shortest-hand yet most reliable metric is daily volume / total shares outstanding.  A security with a high turnover rate will be more efficient than a lower one, ceteris paribus. The practical impacts are tighter spread and lower average percentage change between trades.  A security with a spread of 0% and an average change of 0% between trades is perfectly efficient. "You can't do this automatically; you want to understand whether the drop is from a short-term high. is likely to be a short-term low, or reflects an actual change in how folks expect the company to do in the future. Having said that, some people do favor a strategy which resembles this, betting on what are known as ""the dogs of the Dow"" in the assumption that they're well trusted but not as strongly sought and therefore perhaps not bid up as strongly. I have no opinion on it; I'm just mentioning it for comparison." Your plan will probably work. I speak from past experience approx 5-10 years ago, when Lloyds used to offer tiered interest of up to 4% on £5000 in their Vantage accounts. It was allowed for an individual person to have up to three Vantage accounts. The criteria for obtaining the headline interest rates were simply: What I, and many others, did was to set up three Vantage accounts, call them A, B, and C, and a standing order on each to transfer minimum amount + £1 on the same day each month in this manner: This satisfied the letter of conditions, though perhaps not the spirit. Most importantly it satisfied the bank, and all three accounts received that headline interest rate. These days banks have got a little wiser to this and have started including the 'set up n direct debits' condition, which makes this a more time-consuming system to arrange - you must assign your various bills across your accounts - but I believe that the overall plan still works. They don't care where the money comes from, or whether it stays - just that it comes in. Enough people get it wrong that they don't have to worry about the few who get it perfectly right (see also: how 0% balance transfer offers can be profitable...)