When a Company was expected and then made a profit of X $ then that X$ increased it's share price. or those the Sellers and Buyers [duplicate]
There are a few reason why share prices increase or decrease, the foremost is expectation of the investors that the company/economy will do well/not well, that is expectation of profit/intrinsic value growth over some time frame (1-4 qtrs.)there is also demand & supply mismatch over (usually) short time. If you really see, the actual 'value' of a company is it's net-worth (cash+asset+stock in trade+brand value+other intangibles+other incomes)/no of shares outstanding, which (in a way) is the book value, then all shares should trade at their book value, the actual number but it does not, the expectation of investors that a share would be purchased by another investor at a higher price because the outlook of the company over a long time is good.
First, the stock does represent a share of ownership and if you have a different interpretation I'd like to see proof of that. Secondly, when the IPO or secondary offering happened that put those shares into the market int he first place, the company did receive proceeds from selling those shares. While others may profit afterward, it is worth noting that more than a few companies will have secondary offerings, convertible debt, incentive stock options and restricted stock that may be used down the road that are all dependent upon the current trading share price in terms of how useful these can be used to fund operations, pay executives and so forth. Third, if someone buys up enough shares of the company then they gain control of the company which while you aren't mentioning this case, it is something to note as some individuals buy stock so that they can take over the company which happens. Usually this has more of an overall plan but the idea here is that getting that 50%+1 control of the company's voting shares are an important piece to things here. "It means that the company earned 15 cents per share in the most recently reported quarter. Share price may or not be affected, depending on how buyers and sellers value the company. Just because profits ""jumped,"" does not mean the shares will follow suit. An increase in profits may have already been priced into the stock, or the market expected the increase in profit to be even higher. As the shareholder, you don't actually get any of these profits into your hands, unless the company pays out a portion of these profits as a dividend." Stock prices reflect future expectations of large groups of people, and may not be directly linked to traditional valuations for a number of reasons (not definitive). For example, a service like Twitter is so popular that even though it has no significant revenue and loses money, people are simply betting that it is deeply embedded enough that it will eventually find some way to make money. You can also see a number of cases of IPOs of various types of companies that do not even have a revenue model at all. Also, if there is rapid sales growth in A but B sales are flat, no one is likely to expect future profit growth in B such that the valuation will remain steady. If sales in A are accelerating, there may be anticipation that future profits will be high. Sometimes there are also other reasons, such as if A owns valuable proprietary assets, that will hold the values up. However, more information about these companies' financials is really needed in order to understand why this would be the case. "What does it mean in terms of share price? Should the share price increase by 15 cents?  No, but you're on the right track. In theory, the price of a share reflects it's ""share"" of time discounted future earnings. To put it concretely, imagine a company consistently earning 15 cents a share every year and paying it all out as dividends. If you only paid 25 cents for it, you could earn five cents a share by just holding it for two years. If you imagine that stocks are priced assuming a holding period of 20 years or so, so we'd expect the stock to cost less than 3 dollars.  More accurately, the share price reflects expected future earnings. If everyone is assuming this company is growing earnings every quarter, an announcement will only confirm information people have already been trading based on. So if this 15 cents announcement is a surprise, then we'd expect the stock price to rise as a function of both the ""surprise"" in earnings, and how long we expect them to stay at this new profitability level before competition claws their earnings away. Concretely, if 5 cents a share of that announcement were ""earnings surprise,"" you'd expect it to rise somewhere around a dollar." Simple, there is no magic price adjustment after sales - why do you expect the stock price to change? The listed price of a stock is what someone was willing to pay for it in the last deal that was concluded. If any amount of stock changes ownership, this might have the effect that other people are willing to buy it for a higher price - or not. It is solely in the next buyer's decision what he is willing to pay. Example: if you think Apple stocks are worth 500$ a piece, and I buy a million of them, you might still think they are worth 500$. Or you might see this as a reason that they are worth 505$ now. Would you mind adding where that additional value comes from, if not from the losses of other investors?  You asked this in a comment, but it seems to be the key to the confusion.   Corporations generate money (profits, paid as dividends) from sales.  Sales trade products for money.  The creation of the product creates value.  A car is worth more than General Motors pays for its components and inputs, even including labor and overhead as inputs.  That's what profit is:  added value.  The dividend is the return that the stock owner gets for owning the stock.   This can be a bit confusing in the sense that some stocks don't pay dividends.  The theory is that the stock price is still based on the future dividends (or the liquidation price, which you could also consider a type of dividend).  But the current price is mostly based on the likelihood that the stock price will increase rather than any expected dividends during ownership of the stock.   A comment calls out the example of Berkshire Hathaway.  Berkshire Hathaway is a weird case.  It operates more like a mutual fund than a company.  As such, investors prefer that it reinvest its money rather than pay a dividend.  If investors want money from it, they sell shares to other investors.  But that still isn't really a zero sum game, as the stock increases in value over time.   There are other stocks that don't pay dividends.  For example, Digital Equipment Corporation went through its entire existence without ever paying a dividend.  It merged with Compaq, paying investors for owning the stock.   Overall, you can see this in that the stock market goes up on average.  It might have a few losing years, but pick a long enough time frame, and the market will increase during it.  If you sell a stock today, it's because you value the money more than the stock.  If it goes up tomorrow, that's the buyer's good luck.  If it goes down, the buyer's bad luck.  But it shouldn't matter to you.  You wanted money for something.  You received the money.   The increase in the stock market overall is an increase in value.  It is completely unrelated to trading losses.  Over time, trading gains outweigh trading losses for investors as a group.  Individual investors may depart from that, but the overall gain is added value.   If the only way to make gains in the stock market was for someone else to take a loss, then the stock market wouldn't be able to go up.  To view it as a zero sum game, we have to ignore the stocks themselves.  Then each transaction is a payment (loss) for one party and a receipt (gain) for the other.  But the stocks themselves do have value other than what we pay for them.  The net present value of of future payments (dividends, buyouts, etc.) has an intrinsic worth.  It's a risky worth.  Some stocks will turn out to be worthless, but on average the gains outweigh the losses. "To a certain degree ""the only sure thing I know is the price I paid for the stock is the fair price at the time I buy it"" is absolutely right, by definition, and by the law of the free and efficient market and forces of supply and demand, freedom of public information about share price sensitive information, etc, etc, etc, and you've made a good point that eludes many investors I'd say. However, in practise, the market has many participants, and they will all be arriving at a different idea of what the ""fair price"" is by way of a slightly different analysis and slightly different information. In theory they all have the same information, but unfortunately in practise there is always some disparity. When one participant feels a stock is undervalued though the last thing they want to do is say so, instead they will start buying stock. They might feel it is undervalued by 20%, but that doesn't mean they'll keep buying and buying until it gets to 20%, they might push the price up just a little, then let the price drift down again, buy some more, relax, buy some more, etc. Over time the price will rise of course because the supply will become weaker, but even if the participant is correct about the 20% the price might have only risen 7% by the time they acquire all the stock they want given their risk models, market exposure and margin guidelines, etc, and it might be more than a year later before the price has actually risen to 20%, presumably because more and more other market participants have come to the same conclusion. The opposite can obviously also happen, a participant might dump stock it feels is over valued long before it hits the values it believes in. So right away you can see that pricing might not really reflect value, or ""fair price""." In simplest terms, when a company creates new shares and sells them, it's true that existing shareholders now own a smaller percentage of the company.  However, as the company is now more valuable (since it made money by selling the new shares), the real dollar value of the previous shares is unchanged. That said, the decision to issue new shares can be interpreted by investors as a signal of the company's strategy and thereby alter the market price;  this may well affect the real dollar value of the previous shares.  But the simple act of creating new shares does not alter the value in and of itself. When stocks have a change in price it is because of a TRADE. To have a trade you have to have both a buyer and a seller.  When the price of a security is going up there are an equal amount of shares being sold as being bought. When the price of a security is going down there are an equal amount of shares being bought as being sold.  There almost always is an unequal amount of shares waiting to be sold compared to the amount waiting to be bought. But waiting shares do not move the price, only when the purchase price and the sale price agree, and a trade occurs, does the price move.  So the price does not go down because more shares are being sold. Neither does the price go up because more shares are being bought. "Institutions may be buying large quantities of the stock and would want the price to go up after they are done buying all that they have to buy.  If the price jumps before they finish buying then they may not make as great a deal as they would otherwise.  Consider buying tens of thousands of shares of a company and then how does one promote that?  Also, what kind of PR system should those investment companies have to disclose whether or not they have holdings in these companies.  This is just some of the stuff you may be missing here. The ""Wall street analysts"" are the investment banks that want the companies to do business through them and thus it is a win/win relationship as the bank gets some fees for all the transactions done for the company while the company gets another cheerleader to try to play up the stock." If the market believes that the company is overstaffed, then management acknowledging the issue and resolving the problem can result in the price going up.  It can also mean that external events drove the price up, and the bad news was lost in the other issues of the day. Sometimes layoffs are a sign of the company entering a long downward spiral; in other cases it is a sign of the beginning recovery. The layoffs can also be viewed as good news if they weren't as big as some experts feared.  You have to look at the exact situation to understand why news x impacts the companies price. Day traders see a dip, buy stocks, then sell them 4 mins later when the value climbed to a small peak. What value is created? Is the company better off from that trade? The stocks were already outside of company hands, so the trade doesn't affect them at all. You've just received money from others for no contribution to society. A common scenario is a younger business having a great idea but not enough capital funds to actually get the business going. So, investors buy shares which they can sell later on at a higher value. The investor gets value from the shares increasing over time, but the business also gets value of receiving money to build the business. "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!" Here are some significant factors affect the company stock price performance: Usually, profitability is known to the public through the financial statements; it won't be 100% accurate and people would also trade the stock with the price not matching to the true value of the firm. Still there are dozens of other various reasons exist. People are just not behaving as rational as what the textbook describes when they are trading and investing. You are assuming the price increase will continue. The people selling are assuming that the price increase will not continue.  Ultimately that's what a share transaction is: one person would rather have the cash at a particular price / time, and one person would rather have the share.