Why do stocks tend to trade at high volumes at the end of (or start) the trading day?
"Trading at the start of a session is by far higher than at any other time of the day. This is mostly due to markets incorporating news into the prices of stocks. In other words, there are a lot of factors that can affect a stock, 24 hours a day, but the market trades for only 6.5 hours a day. So, a lot of news accumulates during the time when people cannot trade on that news. Then when markets finally open, people are able to finally trade on that news, and there is a lot of ""price discovery"" going on between market participants. In the last minutes of trading, volumes increase as well. This can often be attributed to certain kinds of traders closing out their position before the end of the day. For example, if you don't want to take the risk a large price movement at the start of the next day affecting you, you would need to completely close your position." Trading at the start of the day is highest because of news flows that may have come after the close of the previous day.  And trading at the end of the day is highest because of expected news flows after closing hours. Moreover, there are many day traders who buy in the morning without making any payment for purchase and such traders have to sell by evening or else they will have to make the payment for the purchases which they have made. Is it possible that mutual funds account for a significant portion of this volume. Investors may decide to buy or sell anytime within a 24 hour period, but the transaction only happened at the close of the market. Therefore at 3:59 pm the mutual fund knows if they will be buying or selling stocks that day.  As nws pointed out the non-market hours are longer and therefore accumulate more news event. Some financial news is specifically given during the time the market is closed. Therefore the reaction to that news has to either be in the morning when the market opens or in the late afternoon if they are trying to anticipate the news.  Also in the US market the early morning trader may be reacting to European market activities. Trading volumes are higher at the end of the day as many traders close their open positions. In the morning however, traders incorporate various factors like performance of worldwide markets overnight, any corporate or government announcements, global macro events, etc. The shift to trading at the close began in 2008. Traders did not want to be caught off guard by surprise news and there was a lot of volatility during the financial crisis, so they would close their position in the evening. Thats how it began. There are two reasons why it sticks around. First, there has been an increase usage of index funds or passive funds. These funds tend to update their positions at the end of the day. From the WSJ: Another factor behind the shift has been the proliferation of passively managed investments, such as index funds. These funds aim to mimic an index, like the S&P 500, by owning the shares that comprise it. Index funds don’t trade as often as active investors, but when they do, it is typically near the market close, traders say. That is because buying or selling a stock at its closing price better aligns their performance with the index they are trying to emulate. The second reason is simply that volume attracts volume. As a result of whats mentioned above, you have a shift to end of day trading, and the corrolary to that is that there is a liquidity shortage from 10am to 3pm. Thus, if you want to buy or sell a stock, but there are few buyers or sellers around, you will significant move the price when you enter your order. Obviously this does not affect retail traders, but imagine hedge funds entering or closing a billion dollar position. It can make a huge impact on price. And one way to mitigate that is to wait until there are more market participants to take the other end of your trade, just as at the end of the day. So this is a self-reinforcing trend that has begun in the markets and will likely stick around. http://www.wsj.com/articles/traders-pile-in-at-the-close-1432768080
"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." The simple answer: The opening price is the price of the first trade of the day and the closing price is the price of the last trade of the day.  And since the stock price change from trade to trade they are usually different. "I'll answer this question: ""Why do intraday traders close their position at then end of day while most gains can be done overnight (buy just before the market close and sell just after it opens). Is this observation true for other companies or is it specific to apple ?"" Intraday traders often trade shares of a company using intraday leverage provided by their firm. For every $5000 dollars they actually have, they may be trading with $100,000, 20:1 leverage as an example. Since a stock can also decrease in value, substantially, while the markets are closed, intraday traders are not allowed to keep their highly leveraged positions opened. Probabilities fail in a random walk scenario, and only one failure can bankrupt you and the firm." "It's a form of market manipulation.   It makes it look like there is high trading volume, which gets attention from speculators and technical traders who see a ton of volume and think that there is some kind of news announcement or something. People start buying it so they don't miss out on whatever it is that ""everyone else"" is doing, and the price goes up." There is no direct relationship between volume and stock price. High volume indicates how much stock is changing hands. That can be because people are enthusiastically buying OR enthusiastically selling... and their reasons for doing so may not agree with your own sense of the future value of the stock. Higher volume may mean that the price is more likely to change during the day, but it can be in either direction -- or in no direction at all if there isn't a general agreement on how to react to some piece of news. It's a possibly interesting datum, but it means nothing in isolation. There are several reasons why this may happen and I will update as I get more information from you. Volumes on that stock look low (supposing that they are either in a factor between 1s and 1000s) so it could well be that there was no volume on that day. If no trades occur then open, high and low are meaningless as they are statistics based on trades that occur that day and no trades occur. Remember that there has to be volume to get a price. The stock may have been frozen by either the exchange or the company for the day. This could be for various reasons including to prevent some illegal activity. In that case no trades were made because the market for that stock was closed. Another possibility is that all trades that day were cancelled by the exchange. The exchange may cancel all trades if there is unusual, potentially fraudulent or other illegal activity on the stock. In this case the last price for that day existed but was rolled back by the exchange and never occurred. This is a rare situation. Although I can't find any holidays on that date it is possible that this is how your data provider marks market holidays. It would be valid to ignore the data in that case as being from a non-market day. I cannot tell if this is possible without knowing exchange information. There is a possibility that some data providers don't receive data for a day or that it gets corrupted. It may be worth checking another source to ensure the integrity of the data that you are receiving. Whichever reason is true, the data provider has made the close equal to the previous day's close as no price movements occurred. Strictly the closing price is the price of the last trade made for that day and so should be null (and open, high and low should be null too and not 0 otherwise the price change on day is very large!). Therefore, to keep integrity, you have a few choices: Something to consider is that in the case of the company you chose, on the OTC market, that stock is thinly traded and with such low volume, it can be easy for it to fluctuate greatly to have trades occur.  This is why volume can matter for some people when it comes to buying shares. Some OTC stocks may have really low volume and thus may have bigger swings than other stocks that have higher volume. There's someone on both sides of every derivatives trade. When volatility goes up, risk goes up, and prices go up. For every dollar lost when that price changes quickly, someone is making a dollar just as quickly. If you're on the right side, you can make a fortune overnight in derivatives when volatility is high; during a normal market, it is much harder and takes much longer. Volumes are used to predict momentum of movement, not the direction of it. Large trading volumes generally tend to create a price breakout in either positive or negative direction. Especially in relatively illiquid stocks (like small caps), sudden volume surges can create sharp price fluctuations. "Most of the investors who have large holdings in a particular stock have pretty good exit strategies for those positions to ensure they are getting the best price they can by selling gradually into the volume over time. Putting a single large block of stock up for sale is problematic for one simple reason: Let's say you have 100,000 shares of a stock, and for some reason you decide today is the day to sell them, take your profits, and ride off into the sunset.  So you call your broker (or log into your brokerage account) and put them up for sale.  He puts in an order somewhere, the stock is sold, and your account is credited. Seems simple, right?  Well...not so fast. Professionals - I'm keeping this simple, so please don't beat me up for it! The way stocks are bought and sold is through companies known as ""market makers"".  These are entities which sit between the markets and you (and your broker), and when you want to buy or sell a stock, most of the time the order is ultimately handled somewhere along the line by a market maker.  If you work with a large brokerage firm, sometimes they'll buy or sell your shares out of their own accounts, but that's another story. It is normal for there to be many, sometimes hundreds, of market makers who are all trading in the same equity.  The bigger the stock, the more market makers it attracts.  They all compete with each other for business, and they make their money on the spread between what they buy stock from people selling for and what they can get for it selling it to people who want it. Given that there could be hundreds of market makers on a particular stock (Google, Apple, and Microsoft are good examples of having hundreds of market makers trading in their stocks), it is very competitive.  The way the makers compete is on price.  It might surprise you to know that it is the market makers, not the markets, that decide what a stock will buy or sell for. Each market maker sets their own prices for what they'll pay to buy from sellers for, and what they'll sell it to buyers for.  This is called, respectively, the ""bid"" and the ""ask"" prices.  So, if there are hundreds of market makers then there could be hundreds of different bid and ask prices on the same stock.  The prices you see for stocks are what are called the ""best bid and best ask"" prices.  What that means is, you are being shown the highest ""bid"" price (what you can sell your shares for) and the best ""ask"" price (what you can buy those shares for) because that's what is required.  That being said, there are many other market makers on the same stock whose bid prices are lower and ask prices are higher.  Many times there will be a big clump of market makers all at the same bid/ask, or within fractions of a cent of each other, all competing for business.  Trading computers are taught to seek out the best prices and the fastest trade fills they can. The point to this very simplistic lesson is that the market makers set the prices that shares trade at.  They adjust those prices based (among other factors) on how much buying and selling volume they're seeing.  If they see a wave of sell orders coming into the system then they'll start marking down their bid prices.  This keeps them from paying too much for shares they're going to have to find a buyer for eventually, and it can sometimes slow down the pace of selling as investors and automated systems notice the price decline and decide to wait to sell.  Conversely, if market makers see a wave of buy orders coming into the system, they'll start marking their ask prices up to maximize their gains, since they're selling you shares they bought from someone else, presumably at a lower price.  But they typically adjust their prices up or down before they actually fill trades.  (sneaky, eh?) Depending on how much volume there is on the shares of the company you're selling, and depending on whether there are more buyers than sellers at the moment, your share sell order may be filled at market by a market maker with no real consequence to the share's price. If the block is large enough then it's possible it will not all sell to one market maker, or it might not all happen in one transaction or even all at the same price. This is a pretty complex subject, as you can see, and I've cut a LOT of corners and oversimplified much to keep it comprehensible.  But the short answer to your question is -- it depends. Hope this helps. Good luck!" The stock market's principal justification is matching investors with investment opportunities.  That's only reasonably feasible with long-term investments.  High frequency traders are not interested in investments, they are interested in buying cheap and selling expensive.  Holding reasonably robust shares for longer binds their capital which is one reason the faster-paced business of dealing with options is popular instead.  So their main manner of operation is leeching off actually occuring investments by letting the investors pay more than the recipients of the investments receive. By now, the majority of stock market business is indirect and tries guessing where the money goes rather than where the business goes. For one thing, this leads to the stock market's evaluations being largely inflated over the actual underlying committed deals happening.  And as the commitment to an investment becomes rare, the market becomes more volatile and instable: it's money running in circles. Fast trading is about running in front of where the money goes, anticipating the market.  But if there is no actual market to anticipate, only people running before the imagination of other people running before money, the net payout converges to zero as the ratio of serious actual investments in tangible targets declines. By and large, high frequency trading converges to a Ponzi scheme, and you try being among the winners of such a scheme.  But there are a whole lot of people competing here, and essentially the net payoff is close to zero due to the large volumes in circulation as opposed to what ends up in actual tangible investments. It's a completely different game with different rules riding on the original idea of a stock market.  So you have to figure out what your money should be doing according to your plans. "Probably the biggest driver of the increased volumes that day was a change in sentiment towards the healthcare sector as a whole that caused many healthcare companies to experience higher volumes ( https://www.bloomberg.com/press-releases/2017-07-11/asset-acquisitions-accelerate-in-healthcare-sector-boosting-potential-revenue-growth ). Following any spike, not just sentiment related spikes, the market tends to bounce back to about where it had been previously as analysts at the investment banks start to see the stock(s) as being overbought or oversold. This is because the effect of a spike on underlying ratios such as the Sharpe ratio or the PE ratio makes the stock look less attractive to buyers and more attractive to sellers, including short sellers. Note, however, that the price is broadly still a little higher than it was before the spike as a result of this change in sentiment. Looking at the price trends on Bloomberg (https://www.bloomberg.com/quote/CDNA:US) the price had been steadily falling for the year prior to the spike but was levelling out at just over $1 in the few months immediately prior to the spike. The increased interest in the sector and the stock likely added to a general change in the direction of the price trend and caused traders (as opposed to investors) to believe that there was a change in the price trend. This will have lead to them trading the stock more heavily intraday exacerbating the spike. Note that there traders will include HFT bots as well as human traders. You question the legality of this volume increase but the simple answer is that we may never know if it was the target of traders manipulating the price or a case of insider trading. What we can see is that (taking ""animal spirits"" into account) without any evidence of illegality there are plenty of potential reasons why the spike may have occurred. Spikes are common where traders perceive a change in a trend as they rush to cash in on the change before other traders can and then sell out quickly when they realise that the price is fundamentally out of sync with the firm's underlying position. You yourself say that you have been watching the stock for some time and, by that fact alone, it is likely that others are for the same reasons that you are. Otherwise you wouldn't be looking at it. Where people are looking at a stock expecting it to take off or drop you expect volatility and volatility means spikes!" "Both explanations are partly true. There are many investors who do not want to sell an asset at a loss.  This causes ""resistance"" at prices where large amounts of the asset were previously traded by such investors.  It also explains why a ""break-through"" of such a ""resistance"" is often associated with a substantial ""move"" in price. There are also many investors who have ""stop-loss"" or ""trailing stop-loss"" ""limit orders"" in effect.  These investors will automatically sell out of a long position (or buy out of a short position) if the price drops (or rises) by a certain percentage (typically 8% - 10%). There are periods of time when money is flowing into an asset or asset class.  This could be due to a large investor trying to quietly purchase the asset in a way that avoids raising the price earlier than necessary.  Or perhaps a large investor is dollar-cost-averaging.  Or perhaps a legal mandate for a category of investors has changed, and they need to rebalance their portfolios.  This rebalancing is likely to take place over time.  Or perhaps there is a fad where many small investors (at various times) decide to increase (or decrease) their stake in an asset class.  Or perhaps (for demographic reasons) the number of investors in a particular situation is increasing, so there are more investors who want to make particular investments.  All of these phenomena can be summarized by the word ""momentum"". Traders who use technical analysis (including most day traders and algorithmic speculators) are aware of these phenomena.  They are therefore more likely to purchase (or sell, or short) an asset shortly after one of their ""buy signals"" or ""sell signals"" is triggered.  This reinforces the phenomena. There are also poorly-understood long-term cycles that affect business fundamentals and/or the politics that constrain business activity.  For example: Note that even if the markets really were a random walk, it would still be profitable (and risk-reducing) to perform dollar-cost-averaging when buying into a position, and also perform averaging when selling out of a position.  But this means that recent investor behavior can be used to predict the near-future behavior of investors, which justifies technical analysis." "Simple answer is because the stocks don't split. Most stocks would have a similar high price per share if they didn't split occasionally.  Why don't they split? A better way to ask this is probably, why DO most stocks split? The standard answer is that it gives the appearance that stocks are ""cheap"" again and encourages investors to buy them. Some people, Warren Buffett (of Berkshire Hathaway) don't want any part of these shenanigans and refuse to split their stocks. Buffett also has commented that he thinks splitting a stock also adds unnecessary volatility." 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.