Are stock prices purely (or mostly) only based on human action?
Stock prices are indeed proportional to supply and demand. The greater the demand for a stock, the greater the price. If they are, would this mean that stock prices completely depend on HOW the public FEELS/THINKS about the stock instead of what it is actually worth? This is a question people have argued for decades. Literature in behavioral finance suggests that investors are not rational and thus markets are subject to wild fluctuation based on investor sentiment. The efficient market theory (EMT) argues that the stock market is efficient and that a stock's price is an accurate reflection of its underlying or intrinsic value. This philosophy took birth with Harry Markovitz's efficient frontier, and Eugene Fama is generally seen as the champion of EMT in the 1960's and onward.  Most investors today would agree that the markets are not perfectly efficient, and that a stock's price does not always reflect its value. The renowned professor Benjamin Graham once wrote: In the short run, the market is a voting machine but in the long run it is a weighing machine. This suggests that prices in the short term are mainly influenced by how people feel about the stock, while in the long run the price reflects what it's actually worth. For example, people are really big fans of tech stocks right now, which suggests why LinkedIn (stock: LNKD) has such a high share price despite its modest earnings (relative to valuation). People feel really good about it, and the price might sustain if LinkedIn becomes more and more profitable, but it's also possible that their results won't be absolutely stellar, so the stock price will fall until it reflects the company's fundamentals.
"Yes, and the reason for that is because things that are above the market (eg regulators, politicians et al) manipulate it constantly.  I think personally the market is still a price discovery mechanism, the rules of the game have just changed. I.e. risk now has taken on additional dimensions, so a lot of conventional theories of asset pricing can effectively be chucked out the window.   Whether we ever see the return to a more ""econ""-driven reality in market expectations (and by that extent therefore asset pricing) is anyone's guess, for now bye-bye to the established light-touch framework of decades past, hello to interventionist randomness." There's only one real list that states what people think stock prices should be, and that's the stocks order book. That lists the prices at which stock owners are willing to buy stocks now, and the price that buyers are willing to pay.  A secondary measure is the corresponding options price. Anything else is just an opinion and not backed by money. Various companies have hired quants to write algorithms to buy and sell stocks. Each of these has unique criteria that determine when it should buy/sell. Most have some AI component that allows it to tweak parameters and learn. The point is the more people try this kind of fake news tactic the better the algorithms get at responding or not responding to it. Keep in mind though that 1) the AIs learn at different rates 2) if an AI notices a boost in trading volume due to a story it determines is fake, the correct move is to buy and then sell before other AIs catch on. "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." 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. "In addition to what @George Marian said, a very large portion of trades are from computer programs trained to make trades when certain apparent patterns are observed.  Since these programs are not all designed in the same way, much of the supply and demand is a result of different algorithms with different ""opinions"" on what the stock is doing." Housing prices are set by different criteria. It can become memoryless the same as the stock if the criteria used to set its price in the past is no longer valid. For example, take Phoenix or Las Vegas - in the past these were considered attractive investments because of the economical growth and the climate of the area. While the climate hasn't changed, the economical growth stopped not only there but also in the places where people buying the houses lived (which is all over the world really). What happened to the housing market? Dropped sharply and stays flat for several years now at the bottom. So it doesn't really matter if the house was worth $300K in Phoenix 5 years ago, you can only sell it now for ~$50K, and that's about it. The prices have been flat low for several years and the house price was $50K, but does it mean its going to stay so? No, once economy gears up, the prices will go up as well. So its not exactly memory-less, but the stocks are not memory-less as well. There is correlation between the past and the future performance. If the environment conditions are similar - the performance is likely to be similar. For stocks however there's much more environment conditions than the housing market and its much harder to predict them. But even with the housing people were burnt a lot on the misconception that the past performance correlates to the future. It doesn't necessarily. There are multiple factors at play that drive stock price movements, but one that can be visualized is that stocks can be priced relative to other (similar stocks).  When one stock price goes up without fundamental changes (i.e. daily market noise/movements), it becomes slightly more expensive relative to it's peers.  Opportunists will sell the now slightly more expensive stock, while others may buying the slightly cheaper (relatively) peer stock.    Imagine millions of transactions like this happening throughout each hour, downward selling pressure on a stock that rises too fast in value relative to it's peers or the market, and upward buying pressure on stocks that are relatively cheaper than it's peers.  It pushes two stocks towards an equilibrium that is directionally the same.    Another way to think of it is lets say tomorrow there is $10B in net new dollars moved into buy orders for stocks that comes from net selling of bonds (this is also partly why bonds/stocks are generally inversely related).  That money goes to buys stocks ABC, XYZ, EFG.  As the price of those goes up with more buying pressure, stocks JKL, MNO, PQR are relatively a tad cheaper, so some money starts to flow into there.  Repeat until you get a large majority of the stocks that buyers are willing to buy and you can see why stocks move in the same direction a lot of times. 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. No, the stock market and investing in general is not a zero sum game.  Some types of trades are zero sum because of the nature of the trade.   But someone isn't necessarily losing when you gain in the sale of a stock or other security. I'm not going to type out a technical thesis for your question.  But the main failure of the idea that investing is zero sum is the fact the a company does not participate in the transacting of its stock in the secondary market nor does it set the price. This is materially different from the trading of options contracts.  Options contracts are the trading of risk, one side of the contract wins and one side of the contract loses. If you want to run down the economic theory that if Jenny bought her shares from Bob someone else is missing out on Jenny's money you're free to do that.  But that would mean that literally every transaction in the entire economy is part of a zero sum game (and really misses the definition of zero sum game). Poker is a zero sum game.  All players bet in to the game in equal amounts, one player takes all the money.  And hell, I've played poker and lost but still sometimes feel that received value in the form of entertainment. "I think ""Psychological Pricing"" is a similar phenomenon to what you are looking for.  This is where retailers use certain numbers in prices because those prices are more appealing to consumers.  Since stocks - and in your case bitcoin - have prices, they too will be more or less appealing at different prices based on psychology alone." Thank you for replying. I'm not sure I totally follow though, aren't you totally at mercy of the liquidity in the stock? I guess I'm havinga hard time visualizing the value a human can add as opposed to say vwapping it or something. I can accept that you're right, just having a difficult time picturing it I think he was trying to say that in the long term the company's fundamental intrinsic value will drive the price of a company's stock, but in the short term stocks move on emotion and publicity that are not necessarily a reflection of their true underlying value. I assert not so. Even if we assume a zero sum game (which is highly in doubt); the general stock market curves indicate the average player is so bad that you don't have to be very good to have better that 50/50 averages. One example: UP stock nosedived right after some political mess in Russia two years ago. Buy! Profit: half my money in a month. I knew that nosedive was senseless as UP doesn't have to care much about what goes on in Russia. Rising oil price was a reasonable prediction; however this is good for railroads, and most short-term market trends behave as if it is bad. In fact markets are not efficient and participants are not rational. That is why we have booms and busts in markets. Emotions and psychology play a role when investors and/or traders make decisions, sometimes causing them to behave in unpredictable or irrational ways. That is why stocks can be undervalued or overvalued compared to their true value.  Also, different market participants may put a different true value on a stock (depending on their methods of analysis and the information they use to base their analysis on). This is why there are always many opportunities to profit (or lose your money) in liquid markets. Doing your research, homework, or analysis can be related to fundamental analysis, technical analysis, or a combination of the two. For example, you could use fundamental analysis to determine what to buy and then use technical analysis to determine when to buy. To me, doing your homework means to get yourself educated, to have a plan, to do your analysis (both FA and TA), to invest or trade according to your plan and to have a risk management strategy in place. Most people are too lazy to do their homework so will pay someone else to do it for them or they will just speculate (on the latest hot tip) and lose most of their money.