What can we learn from when the trading volume is much higher/lower than average?
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.
"Just as a matter of research, apparently there is a way to find high option volumes such as a site here: https://www.barchart.com/options/volume-leaders/stocks However, that information is going to be heavily skewed by ""underlying security that moved a lot more than expected and probably got a lot of positions filled incidentally today"", but I think it is a good place to start building up a list of securities with a lot of option interest. There is also a tab there for ETFs. This will not tell you exactly that a particular stock always has high option volume, but most of the ones that show up there repeatedly and across multiple strike prices will meet your criteria." "I'm not sure the term actually has a clear meaning. We can think of ""what does this mean"" in two ways: its broad semantic/metaphorical meaning, and its mechanical ""what actual variables in the market represent this quantity"". Net buying/selling have a clear meaning in the former sense by analogy to the basic concept of supply and demand in equilibrium markets. It's not as clear what their meaning should be in the latter sense. Roughly, as the top comment notes, you could say that a price decrease is because of net selling at the previous price level, while a price rise is driven by net buying at the previous price level. But in terms of actual market mechanics, the only way prices move is by matching of a buyer and a seller, so every market transaction inherently represents an instantaneous balance across the bid/ask spread. So then we could think about the notion of orders. Actual transactions only occur in balance, but there is a whole book of standing orders at various prices. So maybe we could use some measure of the volume at various price levels in each of the bid/ask books to decide some notion of net buying/selling. But again, actual transactions occur only when matched across the spread. If a significant order volume is added on one side or the other, but at a price far away from the bid/offer - far enough that an actual trade at that price is unlikely to occur - should that be included in the notion of net buying/selling? Presumably there is some price distance from the bid/offer where the orders don't matter for net buying/selling. I'm sure you'd find a lot of buyers for BRK.A at $1, but that's completely irrelevant to the notion of net buying/selling in BRK.A. Maybe the closest thing I can think of in terms of actual market mechanics is the comparative total volumes during the period that would still have been executed if forced to execute at the end of period price. Assuming that traders' valuations are fixed through the period in question, and trading occurs on the basis of fundamentals (which I know isn't a good assumption in practice, but the impact of price history upon future price is too complex for this analysis), we have two cases. If price falls, we can assume all buyers who executed above the last price in the period would have happily bought at the last price (saving money), while all sellers who executed below the last price in the period would also be happy to sell for more. The former will be larger than the latter. If the price rises, the reverse is true." It could be that the contracts were bought at cheaper prices such as $.01 earlier in the day. What you see there with the bid and ask is the CURRENT bid and CURRENT ask. The high ask price means there is no current liquidity, as someone is quoting a very high ask price just in case someone really wants to trade that price. But as you said, no one would buy this with a better price on a closer strike price. The volume likely occurred at a different price than listed on the current ask. I think if you are only trading stocks with average volume greater than 1M you should not have any trouble entering a 10,000 size trade. If you are you can try a couple of things: Change your order from a market order to a limit order, however this may potentially reduce the number of shares that are actually traded on that day, and you may miss out on some or all of your order. Limit your trading to more liquid stocks, say average daily volumes above 10M or 100M. Apart from that you might have to just put up with some extra slippage and incorporate it into your trading plan. That is you can reduce your R multiple to allow some slippage. well well, good question, worth a discussion, the more filters you add to your strategy (volatility in this case), the lower its predictive power. i mean, one could further filter it by day of the week, whether prices are above or below a 200 day moving average...etc. The problem is that while there are a lot of statistics that can be created from basic market data such as prices and volume, along with the fundamentals of the company, I think that if you talk to 8 different day traders, you'll get 12 different theories of how to interpret and trade based on those numbers.  Also quite likely, the more successful someone is at day trading, the more closely they are likely to guard their secrets and not want to divulge them. If there was any uniform concensus, they you'd see all the daytraders doing the same thing, and moving as a group, shortly after which you'd get 'contra' folks who would try to gain by moving in opposition, or 'predicta' folks who would try to front-run the pack. and.... (I think you can see where this leads)  A better idea might be to just work on educating your-self firstly with regard to nomenclature and terms, and then move on to reading some stuff about how markets work   etc.  I'd suggest starting with a book like 'Wall Street Words' and/or 'A Random Walk Down Wall Street' since both are great introductions to things, and move on from there.  Note that both of those books have gone through multiple editions, so be sure to get the most recent one (especially if you are trying to save money and buy a used version)   You are also likely to find an nearly endless supply of 'seminars' that will offer to teach you somebody's proven method for a fee, or for 'free' but after which you find our you need to use their special tools or data sources etc (which cost money) to use their 'system'  (either of which makes me think that their system can't be that great if they figure it's a surer thing to charge for 'teaching' or 'tools/services' than it is to use their system, otherwise they'd just shut up, practice what they preach and make money that way instead)  It might be worth attending the free ones just to get exposure to someone's theory on how to game the system, provided you are 'not an easy mark' and can withstand the high pressure sales pitch for their books/software/services etc that pays their bills and almost invariably comes along with such a seminar. One should also point out that you make a major assumption in that the high of the day doesn't occur on a gap up in morning trading. It's unlikely that you'd fill at a reasonable price, thereby throwing your strategy into disarray. 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. I would say the most challenging fact for this assertion is that HFT firms operate with extremely limited capital bases. For a stock with say 10m shares ADV, even a very large and successful HFT strategy might use a position limit of no more than 5000 shares.  That is to say if you sum up and net the buys and sells for a stock across the day the HFT firm will never exceed 10,000 shares (2x position limits assuming it completely flipped) on a stock that trades 10,000,000 shares on a given day. The high volumes are attained through high turnover, the strategy might trade up to 500,000 shares (or 5% of the volume) attaining a 50x turnover.  But that brings me back to the original point. In the market microstructure literature market impact generally has been found to scale linearly or even sub-linearly for net volume executed.   If I alternate between thousands of 1 lot buy and sell orders, it would be very difficult for me to move the market because the market impact of every one of my buy orders roughly cancels the market impact of my almost exactly equal number of sell orders.   There might be a higher-order mechanism at work, but I'm genuinely curious what you think it might be. How could strategies that attain such small net positions have such out-sized impact on market direction? Consider the case where a stock has low volume.  If the stock normally has a few hundred shares trade each minute and you want to buy 10,000 shares then chances are you'll move the market by driving up the price to find enough sellers so that you can get all those shares.  Similarly, if you sell way more than the typical volume, this can be an issue. The daily Volume is usually compared to the average daily volume over the past 50 days for a stock.  High volume is usually considered to be 2 or more times the average daily volume over the last 50 days for that stock, however some traders might set the crireia to be 3x or 4x the ADV for confirmation of a particular pattern or event. The volume is compared to the ADV of the stock itself, as comparing it to the volume of other stocks would be like comparing apples with oranges, as difference companies would have different number of total stocks available, different levels of liquidity and different levels of volatility, which can all contribute to the volumes traded each day. First, If you buy $10K of a penny stock and try to sell it that afternoon, you probably won't get your money back. The bid/ask spread may cost you dearly.  On the shady side, if you are able to afford to trade enough shares to attract attention, the interest of those who believe the volume is an indication of some real event happening, you may pump it high enough to make some nice money, selling into the ensuing rise. This is a classic pump and dump (which often but not always, includes posts on message boards) and it is illegal. The same way this volume attracts traders, it can also attract the attention of the SEC.  This should be read as a narrative, not as advice. If anything, it's advice on what not to do. All the time. For high volume stocks, it may be tough to see exactly what's going on, e.g. the bid/ask may be moving faster than your connection to the broker can show you.  What I've observed is with options. The volume on some options is measured in the 10's or 100's of contracts in a day. I'll see a case where it's $1.80/$2.00 bid/ask, and by offering $1.90 will often see a fill at that price. Since I may be the only trade on that option in the 15 minute period and note that the stock wasn't moving more than a penny during that time, I know that it was my order that managed to fill between the bid/ask. "I reread your question. You are not asking about the validity of selling a particular stock after a bit of an increase but a group of stocks. We don't know how many.  This is the S&P for the past 12 months. Trading at 1025-1200 or so means that 80-100 points is an 8% move. I count 4 such moves during this time.  The philosophy of ""you can't go wrong taking a gain"" is tough for me to grasp as it offers no advice on when to get (back) in. Studies by firms such as Dalbar (you can google for some of their public material) show data that supports the fact that average investors lag the market by a huge amount. 20 years ending 12/31/08 the S&P returned 8.35%, investor equity returns showed 1.87%. I can only conclude that this is a result of buying high and selling low, not staying the course.  The data also leads me to believe the best advice one can give to people we meet in these circumstances is to invest in index funds, keeping your expenses low as you can. I've said this since read Jack Bogle decades ago, and this advice would have yielded about 8.25% over the 20 years, beating the average investor by far, by guaranteeing lagging the average by 10 basis points or so.  A summary of the more extensive report citing the numbers I referenced is available for down load - QAIB 2015 - Quantitative Analysis of Investor Behavior. It's quite an eye-opener and a worthy read. (The original report was dated 2009, but the link broke, so I've updated to the latest report, 2015)" "Often these types of trades fall into two different categories.   An error by broker or exchange.  Exchange clearing out part of their books incorrectly is an example.  Most exchanges make firms reopen their positions for after market hours.  There may have been an issue doing so or exchange could incorrectly cancel positions.  I was in the direct feed industry for years and this was a big issue.  At the same time the broker can issue a no limit buy on accident (or has software that is prospecting and said software has a bug or written poorly).   unscrupulous parties looking to feign an upswing or downswing in market.  Let's say you hold 500k shares in a stock that sells for $11.  You could possibly buy 100 shares for $13.  Trust me you will find a seller.  Then you are hoping that people see that trade as a ""norm"" and trade from there, allowing you to rake in $1M for spending an extra $200 - NOTE this is not normal and an extreme example.  This was so common in the early days of NASDAQ after hours that they discontinued using the after hours trades as part of historical information that they keep like daily/yearly high or closing price.  The liquidity allows for manipulation.  It isn't seen as much now since this has been done a million times but it does still happen."