How to reconcile these contradictory statements about the effect of volume on stock price?
The first statement is talking about a sudden sharp increase in volume (double or more of average volume) with a sudden increase in price. In other words, there has been a last rush to buy the stock exhausting all the current bulls (buyers), so the bears (sellers) take over, at least temporarily. Whilst the second statement is talking about a gradual increase in volume as the price up trends (thus the use of a volume oscillator). In other words (in an uptrend), the bulls (buyers) are gradually increasing in numbers sending the price higher, and new buyers keep entering the market. (The opposite is the case for a down-trend). These statements aren't necessarily contradictory. In the first case, investors are bearish because they anticipate selling in the future (because all the interested buyers have bought, so all that remains in the short run are people willing to sell and therefore drive down the price).  In the second case, the trend is strengthened because the increase in volume indicates that the price movement interested a lot of traders. The trend could be bullish or bearish.  The statements aren't contradictory because the second case could very well lead to the first case. For example, if an increase in price is coupled with an increase in volume, this could indicate that the positive trend is strengthening (second case). Traders are becoming more interested in the price move, so they buy.  However, once all of the traders who are willing to enter the market long do so, we're in the first case. Investors realize that all of the traders who were interested in buying have bought, so they become bearish because they expect selling to start soon.
Oh, I see what you mean. It depends which side you look at it from: the company, or the individual investor.  For the individual investor, I guess it doesn't matter. As you said, you only buy the amount of stocks you can afford. What matters afterwards is whether the price of your stocks goes up or down. That's when the company valuation comes into play. If a company is overvalued, the stock prices are going to go down until they reach the [equilibrium point](http://en.wikipedia.org/wiki/Economic_equilibrium). Or, rephrasing, stocks go down when more people will want to sell than buy, creating an excess supply, so sellers will be willing to offer lower prices so you buy from them. Stocks go up when the opposite happens, more people will want to buy than sell, so buyers will have to offer more money to convince sellers to sell.  In essence, Facebook was overvalued, and not enough people were buying their shares, creating excess supply, so, sellers had to offer lower prices. Had Facebook been properly valued, people would've felt the stocks were a good price, everyone would've rushed to purchase, and stock prices would've gone up. "This is a classic correlation does not imply causation situation.  There are (at least) three issues at play in this question: If you are swing- or day-trading then the first and second issues can definitely affect your trading.  A higher-price, higher-volume stock will have smaller (percentage) volatility fluctuations within a very small period of time. However, in general, and especially when holding any position for any period of time during which unknowns can become known (such as Netflix's customer-loss announcement) it is a mistake to feel ""safe"" based on price alone. When considering longer-term investments (even weeks or months), and if you were to compare penny stocks with blue chip stocks, you still might find more ""stability"" in the higher value stocks.  This is a correlation alone — in other words, a stable, reliable stock probably has a (relatively) high price but a high price does not mean it's reliable. As Joe said, the stock of any company that is exposed to significant risks can drop (or rise) by large amounts suddenly, and it is common for blue-chip stocks to move significantly in a period of months as changes in the market or the company itself manifest themselves. The last thing to remember when you are looking at raw dollar amounts is to remember to look at shares outstanding.  Netflix has a price of $79 to Ford's $12; yet Ford has a larger market cap because there are nearly 4 billion shares compared to Netflix's 52m." "Note that we do not comment on specific stocks here, and have no place doing so. If your question is only about that specific stock then it is off topic. I have not tried to answer that part below. The key to valuation is predicting the net present value of all of a company's cash flows; i.e. of their future profits and losses. Through a number of methods to long to explain here investment banks and hedge funds work out what they expect the company's cash flows to be and trade so that these future profits, losses etc. are priced into the stock price. Since future cash flows, profits or whatever you want to call them are priced in, the price of a stock shouldn't move at all on an earnings statement. This begs the question ""why do some stock prices move violently when they announce earnings?"" The models that the institutional investors use are not perfect and cannot take into account everything. An unexpected craze for a product or a supply chain agreement breaking down on not being as good as it seems will not be factored into this pricing and so the price will move based on the degree to which expectation is missed or exceeded. Since penny socks are speculative their value is based far more on the long term expected cash flows and less on the short run cash flows. This goes a long way to explaining why some of the highest market capitalisation penny stocks are those making consistent losses. This means that they can be far less susceptible to price movements after an earnings announcement even if it is well out of the consensus range. Higher (potential) future value comes with the higher risks of penny stocks which discounts current value. In the end if people's expectation of the company's performance reflects reality then the profitability is priced in and there will be no price movement. If the actuality is outside of the expected range then there will be a price movement." Buying pressure means there are more interested buyers than there are ready sellers putting upward pressure on prices. That might include institutional buyers who are slowly executing buy orders because they still want the best prices possible without clearing out the market. Buying pressure doesn't have to be related to volume at all. If everyone who owns shares think they are going to be worth far more than recent market prices, they will not offer them for sale. That means there is more demand to buy than there is a supply of shares to be bought. That condition can exist regardless of trading volume. That is mostly true, in most situations when there are more buy orders than sell orders (higher buy volume orders than sell volume orders), the price will generally move upwards and vice versa, when there are more sell orders than buy orders (higher sell volume orders than buy volume orders), the price will generally move downwards. Note that this does not always happen, but usually it does. You are also correct that for a trade to take place a buyer has to be matched with a seller (or the buy volume matched with the sell volume). But not all orders get executed as trades. Say there are 50 buy orders in the order book with a total volume of 100,000 shares and the highest buy order is currently at $10.00. On the other side there are only 10 sell orders in the order book with total volume of 10,000 shares and the lowest sell order is currently $10.05. At the moment there won't be a trade unless a new buyer or seller enters the market to match the opposing side, or an existing order gets amended upper or lower to match the opposing side. With more demand than supply in the order books what will be the most likely direction that this stock moves in? Most likely the price will move upwards. If a new buyer sees the price moving higher and then looks at the market depth, they would most likely place an order closer to the lowest sell order than the current highest buy order, say $10.01, to be first in line in case a market sell order is placed on the market. As new buy orders enter the market it drives the price higher and higher until the buy orders dry up. "It reminds me of the Efficient Market Hypothesis, except that just states in its weakest form that the current market price accounts for all information embedded in previous market prices. In other words, people buying today at 42 know it was selling for 40 yesterday, and the patterns and such. To say that stock is memoryless strikes me as not quite right -- to the extent that stocks are valued based on earnings, much of what we infer about future earnings relies on past and present earnings. One obvious counterexample to this ""memoryless"" claim is bankruptcy. If a stock files bankruptcy, and there isn't enough money to pay senior debt, your shares are worth 0 in perpetuity." "This was an article meant for mass consumption, written by a Yale law professor and an individual who has a PhD in economics (in addition to his practical, on the job experience managing the Yale endowment).  I'm having a hard time believing that it was ""poorly argued.""  As for proof, that's the sort of thing you find in financial and economic journals (for example, [The Effect of Maker-Taker Fees on Investor Order Choice and Execution Quality in U.S. Stock Markets](http://people.stern.nyu.edu/jhasbrou/SternMicroMtg/SternMicroMtg2015/Papers/MakerTakerODonoghue.pdf)).    One of the direct takeaways from the above paper states:  *""I find that total trading cost to investors increases, when the taker fee and maker rebate increase, even if the net fee is held fixed. The total trading cost represents the net-of-fees bid-ask spread and the brokerage commission to an investor wanting to buy and then sell the same stock.""*  I'm not here to argue for the paper.  I'm really here to tell you that these guys have far more of a clue than you realize.  ~~A dash of humility on your part may be in order, given the fact that you've already admitted to the reality that you aren't sure of any of this yourself.~~  *Edit*:  Thought I was responding to a different thread." &gt; One is whether prices are correlated to each other for long periods of time as a preliminary study suggested (which would go against efficient markets hypothesis, since you could use that info to game the market) or if that result is illusory and the long term returns are close to a standard normal distribution which would follow the effiecient markets hypo.  The fascinating thing about this is that the returns themselves show no correlation at all (at any time scale), but the *absolute* returns do.  i.e. following a sharp rise/drop in price, you can predict that a sharp rise/drop is likely to follow, you just can't say in which direction.  And this effect carries over for long periods.  Given that by the central limit theorem the sum of identically distributed random variables converges to a gaussian, leads one to think that short term returns *ought* to be gaussian also.  However, they're not.  Evidently there is something very subtle going on. In my original question, I  was wondering if there was a mathematical convention to help in deciding on whether an equity offering OR debt offering would be a better choice. I should have clarified better in the question, I used Vs. which may have made it unclear. "I've alway thought that it was strange, but the ""price"" that gets quoted on a stock exchange is just the price of the last transaction. The irony of this definition of price is that there may not actually be any more shares available on the market at that price. It's also strange to me that the price isn't adjusted at all for the size of the transaction. A transaction of just 1 share will post a new price even if just seconds earlier 100,000 shares traded for a different price. (Ok, unrealistic example, but you get my point.) I've always believed this is an odd way to describe the price. Anyway, my diatribe here is supposed to illustrate the point that the fluctuations you see in price don't really reflect changing valuations by the stock-owning public. Each post in the exchange maintains a book of orders, with unmatched buy orders on one side and unmatched sell orders on the other side. If you go to your broker and tell him, ""fill my order for 50,000 shares at market price"", then the broker won't fill you 50,000 shares at .20. Instead, he'll buy the 50 @ .22, then 80 @ .23, then 100 @ .30, etc. Because your order is so large compared to the unmatched orders, your market order will get matched a bunch of the unmatched orders on the sell side, and each match will notch the posted price up a bit. If instead you asked the broker, ""open a limit order to buy 50000 shares at .20"", then the exchange will add your order to the book: In this case, your order likely won't get filled at all, since nobody at the moment wants to sell at .20 and historically speaking it's unlikely that such a seller will suddenly appear. Filling large orders is actually a common problem for institutional investors: http://www.businessweek.com/magazine/content/05_16/b3929113_mz020.htm http://www.cis.upenn.edu/~mkearns/papers/vwap.pdf (Written by a professor I had in school!)" Ideally, stock price reflects the value of the company, the dividends it is expected to pay, and what people expect the future value of the company to be. Only one of those (maybe one and a half) is related to current  sales, and not always directly. Short-term motion of a stock is even less directly linked, since it also reflects previous expectations. A company can announce disappointing sales and see its stock go up, if the previous price was based on expecting  worse news. "What most of these answers here seem to be missing is that a stock ""price"" is not exactly what we typically expect a price to be--for example, when we go in to the supermarket and see that the price of a gallon of milk is $2.00, we know that when we go to the cash register that is exactly how much we will pay.  This is not, however, the case for stocks. For stocks, when most people talk about the price or quote, they are really referring to the last price at which that stock traded--which unlike for a gallon of milk at the supermarket, is no guarantee of what the next stock price will be.  Relatively speaking, most stocks are extremely liquid, so they will react to any information which the ""market"" believes has a bearing on the value of their underlying asset almost (if not) immediately.  As an extreme example, if allegations of accounting fraud for a particular company whose stock is trading at $40 come out mid-session, there will not be a gradual decline in the price ($40 -> $39.99 -> $39.97, etc.)-- instead, the price will jump from $40 to say, $20.  In the time between the the $40 trade and the $20 trade, even though we may say the price of the stock was $40, that quote was actually a terrible estimate of the stock's current (post-fraud announcement) price. Considering that the ""price"" of a stock typically does not remain constant even in the span of a few seconds to a few minutes, it should not be hard to believe that this price will not remain constant over the 17.5 hour period from the previous day's close to the current day's open.  Don't forget that as Americans go to bed, the Asian markets are just opening, and by the time US markets have opened, it is already past 2PM in London.  In addition to the information (and therefore new knowledge) gained from these foreign markets' movements, macro factors can also play an important part in a security's price-- perhaps the ECB makes a morning statement that is interpreted as negative news for the markets or a foreign government before the US markets open.  Stock prices on the NYSE, NASDAQ, etc. won't be able to react until 9:30, but the $40 price of the last trade of a broad market ETF at 4PM yesterday probably isn't looking so hot at 6:30 this morning... don't forget either that most individual stocks are correlated with the movement of the broader market, so even news that is not specific to a given security will in all likelihood still have an impact on that security's price. The above are only a few of many examples of things that can impact a stock's valuation between close and open: all sorts of geopolitical events, announcements from large, multi-national companies, macroeconomic stats such as unemployment rates, etc. announced in foreign countries can all play a role in affecting a security's price overnight. As an aside, one of the answers mentioned after hours trading as a reason--in actuality this typically has very little (if any) impact on the next day's prices and is often referred to as ""amateur hour"", due to the fact that trading during this time typically consists of small-time investors.  Prices in AH are very poor predictors of a stock's price at open." "To your first comment: yup. To your second comment, A = L + E. If E goes down, and L goes up, the net effect is 0. Then, if L goes down, and A goes up, the net effect is 0 and we are balanced once again. There is no ""rebalancing"" equity. You just have to make sure that, at the end of your journal entries, the accounting equation holds.  It's a very unintuitive concept to wrap your head around, but spend some time mapping out the flow of various journal entries. Once it clicks, you'll really understand the logic." Yep, you have it pretty much right.   The volume is the number of shares traded that day. The ticker is giving you the number of shares bought at that price in a given transaction, the arrow meaning whether the stock is up or down on the day at that price.   Institutional can also refer to pensions, mutuals funds, corporates; generally any shareholder that isn't an individual person. K, welcome to Money.SE.  You knew enough to add good tags to the question. Now, you should search on the dozens of questions with those tags to understand (in less than an hour) far more than that banker knows about credit and credit scores.  My advice is first, never miss a payment. Ever. The advice your father passed on to you is nonsense, plain and simple. I'm just a few chapters shy of being able to write a book about the incorrect advice I'd heard bank people give their customers. The second bit of advice is that you don't need to pay interest to have credit cards show good payment history. i.e. if you choose to use credit cards, use them for the convenience, cash/rebates, tracking, and guarantees they can offer. Pay in full each bill.  Last - use a free service, first, AnnualCreditReport.com to get a copy of your credit report, and then a service like Credit Karma for a simulated FICO score and advice on how to improve it. As member @Agop has commented, Discover (not just for cardholders) offers a look at your actual score, as do a number of other credit cards for members.  (By the way, I wouldn't be inclined to discuss this with dad. Most people take offense that you'd believe strangers more than them. Most of the answers here are well documented with links to IRS, etc, and if not, quickly peer-reviewed. When I make a mistake, a top-rated member will correct me within a day, if not just minutes)