Are traders 100% responsible for a stock's price changes?
"Traders = every market participant. Not some shadow figure that excludes you just because you passively drop cash into a 401k Vanguard fund every paycheck. So yes, if everyone stopped trading then the price won't move. Trades are 100% responsible for the prices you see on charts and tickers. A stock won't be worth ""$100"" if nobody ever traded $100 for it. It only has that price now or in the past because somebody placed an order for it at $100 and somebody else filled that order at $100" "When people talk about ""the price"" of a stock, they usually mean one of the following: Last price:  The price at which a trade most recently took place.  If someone sold (and someone else bought) shares of XYZ for $20 each, then until another trade occurs, the last price of the stock will be quoted at $20. Bid price: The highest price at which someone is currently offering to buy the stock. Ask price: The lowest price at which someone is currently offering to sell the stock. As you can see, all of these are completely determined by the people buying and selling the stock." Value is the key word here. Traders should ideally trade on the perceived future value of a company.  Changes in the perceived future value is what leads them to buy and sell shares. That said, if a company were to have some catastrophe happen (say it and all of its employees and property disappeared)  and somehow every shareholder agreed to not sell, the companies market capitalization would remain unmoved even though the value of the company is gone. So theoretically yes, but it is unlikely. "Yes, the value of a stock is completely, 100% determined by what people are willing to pay for it in conjunction with what people who have it are willing to sell it for. If something really bad happened to a company, like their only factory burned to the ground, and the traders didn't care, then I guess, in that scenario, the value of the stock would not change. But you can spin all sorts of hypotheticals of that sort. If dogs could talk, would German Shepherds speak German? Etc. Any answer is pretty meaningless because the premise is wildly unlikely. As CQM notes, ""traders"" in this context means everyone who buys or sells stock. If you buy stock, that includes you. They're not some mystical cabal somewhere. If you see a stock listed at, whatever, $50, and you are not willing to pay more than $40 for it, then you refuse to buy, and so you tend to force the price down. If you're not a billionaire, then your impact on the market is tiny, but the market is made up of millions of people each with tiny influence. Note that all this is true not just of the stock market, but of every product on the market. A product is worth whatever the owner is willing to sell it for and people are willing to pay. This is what determines the price of everything from houses to toasters. It's a little theory I've invented that I like to call, ""the law of supply and demand"". :-)" Yes traders, living or algorithmic, are the only direct factors that can cause a change in the price of a marketable item. Traders can be affected by news, broken exchanges ;), emotional cycles, lunar cycles, time the trader goes to lunch (or a power cycle if you are an algo running on that unfortunate OS), anything.
Investment banks will put out various reports and collect revenues from that along with their banking activity.  I don't read them or care to read them myself.  If banks can make money from something, they will likely do it, especially if it is legal. To take the Tesla stock question for a moment: Aren't you ruling out that yesterday was the day that Tesla was included in the Nasdaq 100 and thus there may be some people today exiting because they tried to cash in on the index funds having to buy the stock and bid it up in a sense?  Or as @littleadv points out there could be those tracking the stocks not in the index that would have been forced to sell for another idea here. The Goldman note is a possible explanation but there could well be more factors in play here such as automated trading systems that seek to take advantage of what could be perceived as arbitrage opportunities. There can be quick judgments made on things which may or may not be true in the end.  After all, who knows exactly what is causing the sell-off.  Is it a bunch of stop orders being triggered?  Is it people actually putting in sell order manually?  Is it something else?  There are lots of questions here where I'm not sure how well one can assign responsibility here. Investopedia has a section in their article about currency trading that states: The FX market does not have commissions. Unlike exchange-based markets, FX is a principals-only market. FX firms are dealers, not brokers. This is a critical distinction that all investors must understand. Unlike brokers, dealers assume market risk by serving as a counterparty to the investor's trade. They do not charge commission; instead, they make their money through the bid-ask spread. Principals-only means that the only parties to a transaction are agents who actively bear risk by taking one side of the transaction.  There are forex brokers who charge what's called a commission, based on the spread. Investopedia has another article about the commission structure in the forex market that states: There are three forms of commission used by brokers in forex. Some firms offer a fixed spread, others offer a variable spread and still others charge a commission based on a percentage of the spread.  So yes, there are forex brokers who charge a commission, but this paragraph is saying mostly the same thing as the first paragraph. The brokers make their money through the bid-ask spread; how they do so varies, and sometimes they call this charge a commission, sometimes they don't. All of the information above differs from the stock markets, however, in which  The broker takes the order to an exchange and attempts to execute it as per the customer's instructions. For providing this service, the broker is paid a commission when the customer buys and sells the tradable instrument. The broker isn't taking a side in the trade, so he's not making money on the spread. He's performing the service of taking the order to an exchange an attempting to execute it, and for that, he charges a commission. People are trying ideas like this, actually.  Though they generally aren't very public about it.  While keshlam ventures into hyperbole when mentioning Watson, he is certainly correct human language parsing is a extremely hard problem. While it is not always true that the big players will know before the news (sometimes that would qualify as insider trading).  The volume spike that you mention generally comes as the news arrives to the major (and minor) players.  So, if you have an algorithm run after the volume spike the price will likely have adjusted significantly already. You can try to avoid this by constantly scanning for news on a set of stocks however this becomes an even harder problem.  Or maybe by becoming more specific and parsing known important and specific news sources (farm report for instance) and trying to do so faster than anyone else.  These are some methods people use to not be too late. "Assuming these are standardized and regulated contracts, the short answer is yes.  In your example, Trader A is short while Trader B is long.  If Trader B wants to exit his long position, he merely enters a ""sell to close"" order with his broker. Trader B never goes short as you state.  He was long while he held the contract, then he ""sold to close"". As to who finds the buyer of Trader B's contract, I believe that would be the exchange or a market maker.  Therefore, Trader C ends up the counterparty to Trader A's short position after buying from Trader B.  Assuming the contract is held until expiration, Trader A is responsible for delivering contracted product to Trader C for contracted price.  In reality this is generally settled up in cash, and Trader A and Trader C never even know each other's identity." "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." "I may be underestimating your knowledge of how exchanges work; if so, I apologize.  If not, then I believe the answer is relatively straightforward. Lets say price of a stock at time t1 is 15$ .  There are many types of price that an exchange reports to the public (as discussed below); let's say that you're referring to the most recent trade price.  That is, the last time a trade executed between a willing buyer and a willing seller was at $15.00. Lets say a significant buy order of 1M shares came in to the market. Here I believe might be a misunderstanding on your part.  I think you're assuming that the buy order must necessarily be requesting a price of $15.00 because that was the last published price at time t1.  In fact, orders can request any price they want.  It's totally okay for someone to request to buy at $10.00.  Presumably nobody will want to sell to him, but it's still a perfectly valid buy order. But let's continue under the assumptions that at t1: This makes the bid $14.99 and the ask $15.00.  (NYSE also publishes these prices.) There aren't enough people selling that stock. It's quite rare (in major US equities) for anyone to place a buy order that exceeds the total available shares listed for sale at all prices.  What I think you mean is that 1M is larger than the amount of currently-listed sell requests at the ask of $15.00. So say of the 1M only 100,000 had a matching sell order and others are waiting. So this means that there were exactly 100,000 shares waiting to be sold at the ask of $15.00, and that all other sellers currently in the market told NYSE they were only willing to sell for a price of $15.01 or higher.  If there had been more shares available at $15.00, then NYSE would have matched them. This would be a trigger to the automated system to start increasing the price. Here is another point of misunderstanding, I think.  NYSE's automated system does not invent a new, higher price to publish at this point.  Instead it simply reports the last trade price (still $15.00), and now that all of the willing sellers at $15.00 have been matched, NYSE also publishes the new ask price of $15.01.  It's not that NYSE has decided $15.01 is the new price for the stock; it's that $15.01 is now the lowest price at which anyone (known to NYSE) is willing to sell.  If nobody happened to be interested in selling at $15.01 at t1, but there were people interested in selling at $15.02, then the new published ask would be $15.02 instead of $15.01 -- not because NYSE decided it, but just because those happened to be the facts at the time. Similarly, the new bid is most likely now $15.00, assuming the person who placed the order for 1M shares did not cancel the remaining unmatched 900,000 shares of his/her order.  That is, $15.00 is now the highest price at which anyone (known to NYSE) is willing to buy. How much time does the automated system wait to increment the price, the frequency of the price change and by what percentage to increment etc. So I think the answer to all these questions is that the automated system does none of these things.  It merely publishes information about (a) the last trade price, (b) the price that is currently the lowest price at which anyone has expressed a willingness to sell, and (c) the price that is currently the highest price at which anyone has expressed a willingness to buy. ::edit:: Oh, I forgot to answer your primary question. Can we estimate the impact of a large buy order on the share price? Not only can we estimate the impact, but we can know it explicitly.  Because the exchange publishes information on all the orders it knows about, anyone tracking that information can deduce that (in this example) there were exactly 100,000 shares waiting to be purchased at $15.00.  So if a ""large buy order"" of 1M shares comes in at $15.00, then we know that all of the people waiting to sell at $15.00 will be matched, and the new lowest ask price will be $15.01 (or whatever was the next lowest sell price that the exchange had previously published)." "There are people (well, companies) who make money doing roughly what you describe, but not exactly. They're called ""market makers"". Their value for X% is somewhere on the scale of 1% (that is to say: a scale at which almost everything is ""volatile""), but they use leverage, shorting and hedging to complicate things to the point where it's nothing like a simple as making a 1% profit every time they trade. Their actions tend to reduce volatility and increase liquidity. The reason you can't do this is that you don't have enough capital to do what market makers do, and you don't receive any advantages that the exchange might offer to official market makers in return for them contracting to always make both buy bids and sell offers (at different prices, hence the ""bid-offer spread""). They have to be able to cover large short-term losses on individual stocks, but when the stock doesn't move too much they do make profits from the spread. The reason you can't just buy a lot of volatile stocks ""assuming I don't make too many poor choices"", is that the reason the stocks are volatile is that nobody knows which ones are the good choices and which ones are the poor choices. So if you buy volatile stocks then you will buy a bunch of losers, so what's your strategy for ensuring there aren't ""too many""? Supposing that you're going to hold 10 stocks, with 10% of your money in each, what do you do the first time all 10 of them fall the day after you bought them? Or maybe not all 10, but suppose 75% of your holdings give no impression that they're going to hit your target any time soon. Do you just sit tight and stop trading until one of them hits your X% target (in which case you start to look a little bit more like a long-term investor after all), or are you tempted to change your strategy as the months and years roll by? If you will eventually sell things at a loss to make cash available for new trades, then you cannot assess your strategy ""as if"" you always make an X% gain, since that isn't true. If you don't ever sell at a loss, then you'll inevitably sometimes have no cash to trade with through picking losers. The big practical question then is when that state of affairs persists, for how long, and whether it's in force when you want to spend the money on something other than investing. So sure, if you used a short-term time machine to know in advance which volatile stocks are the good ones today, then it would be more profitable to day-trade those than it would be to invest for the long term. Investing on the assumption that you'll only pick short-term winners is basically the same as assuming you have that time machine ;-) There are various strategies for analysing the market and trying to find ways to more modestly do what market makers do, which is to take profit from the inherent volatility of the market. The simple strategy you describe isn't complete and cannot be assessed since you don't say how to decide what to buy, but the selling strategy ""sell as soon as I've made X% but not otherwise"" can certainly be improved. If you're keen you can test a give strategy for yourself using historical share price data (or current share price data: run an imaginary account and see how you're doing in 12 months). When using historical data you have to be realistic about how you'd choose what stocks to buy each day, or else you're just cheating at solitaire. When using current data you have to beware that there might not be a major market slump in the next 12 months, in which case you won't know how your strategy performs under conditions that it inevitably will meet eventually if you run it for real. You also have to be sure in either case to factor in the transaction costs you'd be paying, and the fact that you're buying at the offer price and selling at the bid price, you can't trade at the headline mid-market price. Finally, you have to consider that to do pure technical analysis as an individual, you are in effect competing against a bank that's camped on top of the exchange to get fastest possible access to trade, it has a supercomputer and a team of whizz-kids, and it's trying to find and extract the same opportunities you are. This is not to say the plucky underdog can't do well, but there are systematic reasons not to just assume you will. So folks investing for their retirement generally prefer a low-risk strategy that plays the averages and settles for taking long-term trends." The short answer to your question is yes.  Company performance affects stock price only through investors' views. But note that selling for higher and lower prices when the company is doing well or poorly is not an arbitrary choice.  A stock is a claim on the future cash flows of the firm, which ultimately come from its future profits.  If the company is doing well, investors will likely expect that there will large cash flows (dividends) in the future and be willing to pay more to hold it (or require more to sell it).   The price of a stock is equal what people think the future dividends are worth.  If market participants started behaving irrationally, like not reacting to changes in the expected future cash flows, then arbitrageurs would make a ton of money trading against them until the situation was rectified. "The argument you are making here is similar to the problem I have with the stronger forms of the efficient market hypothesis.  That is if the market already has incorporated all of the information about the correct prices, then there's no reason to question any prices and then the prices never change.  However, the mechanism through which the market incorporates this information is via the actors buying an selling based on what they see as the market being incorrect. The most basic concept of this problem (I think) starts with the idea that every investor is passive and they simply buy the market as one basket.  So every paycheck, the index fund buys some more stock in the market in a completely static way.  This means the demand for each stock is the same.  No one is paying attention to the actual companies' performance so a poor performer's stock price never moves.  The same for the high performer.  The only thing moving prices is demand but that's always up at a more or less constant rate. This is a topic that has a lot of discussion lately in financial circles.  Here are two articles about this topic but I'm not convinced the author is completely serious hence the ""worst-case scenario"" title. These are interesting reads but again, take this with a grain of salt.  You should follow the links in the articles because they give a more nuanced understanding of each potential issue.  One thing that's important is that the reality is nothing like what I outline above. One of the links in these articles that is interesting is the one that talks about how we now have more indexes than stocks on the US markets.  The writer points to this as a problem in the first article, but think for a moment why that is.  There are many different types of strategies that active managers follow in how they determine what goes in a fund based on different stock metrics.  If a stocks P/E ratio drops below a critical level, for example, a number of indexes are going to sell it.  Some might buy it.  It's up to the investors (you and me) to pick which of these strategies we believe in. Another thing to consider is that active managers are losing their clients to the passive funds.  They have a vested interest in attacking passive management." A stock's price does not move in a completely continuous fashion.  It moves in discrete steps depending on who is buying/selling at given prices. I'm guessing that by opening bell the price for buying/selling a particular stock has changed based on information obtained overnight. A company's stock closes at $40.  Overnight, news breaks that the company's top selling product has a massive defect.  The next morning the market opens.  Are there any buyers of the stock at $40?  Probably not.  The first trade of the stock takes place at $30 and is thus, not the same as the previous day's close. Many exchanges trade the same securities.  An order may be posted to a secondary exchange, but if the National Best Bid and Offer data provider malfunctions, only those with data feeds from that exchange will see it. Only the data provider for the primary exchange where a stock is listed provides the NBBO. Missing orders are very common with the NBBO data providers.  NASDAQ's order consolidator has had many failures over the past few years, and the data provider's top executive has recently resigned. Brokers have no control over this system.  A broker may be alerted to a malfunction by an accountholder, but a broker may only inform the relevant exchange and the relevant data provider. Stock price is based on supply and demand. Unless the stock you are looking to buy usually has very low volume trading 100 shares isn't likely to have any effect on price. There are many companies that have millions or tens of millions of shares trade daily. For stocks like that 100 shares is barely a trivial percentage of the daily volume. For thinly traded stocks you can look at the bid and ask size but even that isn't likely to get you an exact answer. Unless you are trading large volumes your trade will have no effect on the price of shares. You can definitely affect the price - putting in a buy increases the demand for the stock, causing a permanent price move.  Also if you hammer the market trying to execute too quickly you can hit offers that are out of the money and move the price temporarily before it stabilizes to its new equilibrium.   True, as an individual investor your trades will be negligible in size and the effect will be nonexistent. But if you are a hedge fund putting in a buy for 5% of dtv,  you can have a price impact. not 50%, but at least a handful of bps. A stock is only worth what someone is willing to pay for it. If it trades different values on different days, that means someone was willing to pay a higher price OR someone was willing to sell at a lower price.  There is no rule to prevent a stock from trading at $10 and then $100 the very next trade... or $1 the very next trade. (Though exchanges or regulators may halt trading, cancel trades, or impose limits on large price movements as they deem necessary, but this is beside the point I'm trying to illustrate). Asking what happens from the close of one day to the open of the next is like asking what happens from one trade to the next trade... someone simply decided to sell or pay a different price.  Nothing needs to have happened in between. It is unlikely that buying 100 shares will have any effect on a stock's price, unless the stock's average trading volume is incredibly low.  That being said, no matter how many share you buy, there's no way to know what the impact on the price will be, because that's only one factor in how shares are priced.  If anyone could figure out the answer to your question then they'd be extremely rich, because they'd simply watch for big share trades and then buy those stocks on the way up. The market makers who actually execute the trades are the ones who set the prices, and most stocks have multiple market makers trading the stock, so the bid/ask you see is the highest bid and lowest ask.  The market makers set the price based on what the trend of the stock is.  If, for instance, there's a large number of sell orders against a stock, the market makers will start dropping the bid prices as they fill execution orders, and as they see buy orders increase, they'll raise ask prices as they fill execution orders.  The market makers earn the difference between what they paid to buy someone's stock who was selling and what they get from someone else who buys it. This is a simplified explanation, so pro traders, don't beat me up! (grin) So, basically, it takes quite a bit of share volume in one direction or another to affect a stock's price.  I can guarantee a 100-share trade wouldn't even be noticed by market makers. I hope this helps. Good luck!