How often does a stock price change and where is this defined?
"Stocks prices are determined whenever a buyer and seller agree to trade at a given price. The company (you use AAPL as an example) doesn't set its own stock price. Rather, the investors set the price every time it trades. There's no ""official"" price -- just the last trade. Likewise, you can offer to trade a stock at whatever price you want: that's the definition of a limit order. You might not find a willing buyer or seller at that price, but you can certainly open an order. Stock quotes that you get from your broker or a finance web site reflect the price as last traded. These quotes are updated throughout the trading day and the frequency and delay varies amongst quote providers. Like Knuckle-Dragger suggests in the comments, there are ways to get real-time quotes. It's often more helpful to think in terms of bid/ask instead of ""official price"". See this question for details."
"Buying pressure is when there are more buy orders than sell orders outstanding.  Just because someone wants to buy a stock doesn't mean there's a seller ready to fill that order.  When there's buying pressure, stock prices rise.  When there's selling pressure, stock prices fall. There can be high volume where buying and selling are roughly equal, in which case share prices wouldn't move much. The market makers who actually fill buy and sell orders for stock will raise share prices in the face of buying pressure and lower them in the face of selling pressure.  That's because they get to keep the margin between what they bought shares from a seller for and what they can sell them to a new buyer for.  Here's an explanation from InvestorPlace.com about ""buying pressure"": Buying pressure can basically be defined as increasingly higher demand for a particular stock's shares. This demand for shares exceeds the supply and causes the price to rise. ... The strength or weakness of a stock determines how much buying or selling interest will be required to break support and resistance areas. I hope this helps!" No. The long-term valuation of currencies has to do with Purchasing Power Parity.  The long-term valuation of stocks has to do with revenues, expenses, market sizes, growth rates, and interest rates. In the short term, currency and stock prices change for many reasons, including interest rate changes, demand for goods and services, asset price changes, political fears, and momentum investing.  In any given time window, a currency or stock might be: The Relative Strength Index tries to say whether a currency or stock has recently been rising or falling; it does not inherently say anything about whether the current value is high or low. This can be done, you can be prosecuted for some forms of it, in any case there are more riskless ways of doing what you suggested. First, buying call options from market makers results in market makers buying shares at the same delta as the call option. (100 SHARES X DELTA = How many shares MM's bought). You can time this with the volume and depth of the shares market to get a bigger resulting move caused by your options purchase to get bigger quote changes in your option. So on expiration day you can be trade near at the money options back and forth between being out the money and in the money. You would exit the position into liquidity at a profit. The risk here is that you can be sitting on a big options position, where the commissions costs get really big, but you can spread this out amongst several options contracts. Second, you can again take advantage of market maker inefficiencies by getting your primary position (whether in the share market or options market) placed, and then your other position being a very large buy order a few levels below the best bid. Many market makers and algorithms will jump in front of your, they think they are being smart, but it will raise the best bid and likely make a few higher prints for the mark, raising the price of your call option. And eventually remove your large buy order. Again, you exit into liquidity. This is called spoofing. There have been some regulatory actions against people in doing this in the last few years. As for consequences, you need to put things into perspective. US capital market regulators have the most nuanced regulations and enforcement actions of worldwide capital market regulators, and even then they get criticized for being unable or unwilling to curb these practices. With that perspective American laws are basically a blueprint on what to do in 100 other country's stock exchanges, where the legislature has never gotten around to defining the same laws, the securities regulator is even more underfunded and toothless, and the markets more inefficient. Not advice, just reality. Having gone though this type of event a few times it won't be a problem. On a specific date they will freeze your accounts. Then they will transfer the funds from custodian X to custodian Y. It should only take a day or two, and they will work it around the paydays so that by the time the next paycheck is released everything is established in the new custodian.  Long before the switch over they will announce the investment options in the new company. They will provide descriptions of the options, and a default mapping: S&P 500 old company to S&P 500 new company, International fund old company to international fund new company...  If you do nothing then on the switchover they will execute the mapped switches. If you want to take this an an opportunity to rebalance, you can make the changes to the funds you invest in prior to the switch or after the switch. How you contributions are invested will follow the same mapping rules, but the percentage of income won't change. Again you can change how you want to invest your contributions or matching funds by altering the contribution forms, but if you don't do anything they will just follow the mapping procedures they have defined.  Loans terms shouldn't change.  Company stock will not be impacted. The only hiccup that I would worry about is if the old custodian had a way for you to transfer funds into any fund in their family, or to purchase any individual stock. The question would be does the new custodian have the same options. If you have more questions ask HR or look on the company benefits website. All your funds will be moved to the new company, and none of these transfers will be a taxable event. Edit February 2014: based on this question: What are the laws or rules on 401(k) loans and switching providers? I reviewed the documents for the most recent change (February 2014). The documents from the employer and the new 401K company say: there are no changes to the loan balances, terms, and payment amounts. Although there is a 2 week window when no new loans can be created. All employees received notice 60 days prior to the switchover regarding new investments options, blackout periods. "The Dow Jones Industrial Average (DJIA) is a Price-weighted index.  That means that the index is calculated by adding up the prices of the constituent stocks and dividing by a constant, the ""Dow divisor"".  (The value of the Dow divisor is adjusted from time to time to maintain continuity when there are splits or changes in the roster.)  This has the curious effect of giving a member of the index influence proportional to its share price.  That is, if a stock costing $100 per share goes up by 1%, that will change the index by 10 times as much as if a stock costing $10 per share goes up by the same 1%. Now look at the price of Google.  It's currently trading at just a whisker under $700 per share.  Most of the other stocks in the index trade somewhere between $30 and $150, so if Google were included in the index it would contribute between 5 and 20 times the weight of any other stock in the index.  That means that relatively small blips in Google's price would completely dominate the index on any given day.  Until June of 2014, Apple was in the same boat, with its stock trading at about $700 per share.  At that time, Apple split its stock 7:1, and after that its stock price was a little under $100 per share.  So, post-split Apple might be a candidate to be included in the Dow the next time they change up the components of the index.  Since the Dow is fixed at 30 stocks, and since they try to keep a balance between different sectors, this probably wouldn't happen until they drop another technology company from the lineup for some reason.  (Correction: Apple is in the DJIA and has been for a little over a year now.  Mea culpa.) The Dow's price-weighting is unusual as stock indices go.  Most indices are weighted by market capitalization.  That means the influence of a single company is proportional to its total value.  This causes large companies like Apple to have a lot of influence on those indices, but since market capitalization isn't as arbitrary as stock price, most people see that as ok.  Also, notice that I said ""company"" and not ""stock"".  When a company has multiple classes of share (as Google does), market-cap-weighted indices include all of the share classes, while the Dow has no provision for such situations, which is another, albeit less important, reason why Google isn't in the Dow.  (Keep this in mind the next time someone offers you a bar bet on how many stocks are in the S&P 500.  The answer is (currently) 505!) Finally, you might be wondering why the Dow uses such an odd weighting in its calculations.  The answer is that the Dow averages go back to 1896, when Charles Dow used to calculate the averages by hand.  If your only tools are a pencil and paper, then a price-weighted index with only 30 stocks in it is a lot easier to calculate than a market-cap-weighted index with hundreds of constituents. About the Dow Jones Averages. Dow constituents and prices Apple's stock price chart. The split in 2014 is marked.  (Note that prices before the split are retroactively adjusted to show a continuous curve.)" That metric is not very useful for anything other than very extremely long trading periods. Most strategies or concerned with price movement over much shorter time frames, 15 mins, 1 hr, 4 hr, daily, weekly, monthly. The MA or moving average is a trend following lagging indicator used to smooth out price fluctuations and more accurately reflect the price of trading instrument such as a stock (AAPL), commodity, or currency pair. Traders are generally concerned with current market trends and price action of the instrument they are trading. As such, an extremely long MA (average daily price, over a period of 365 days) are generally not that important. "If the time horizon is not indicated, this is just a ""fair price"". The price of the stock, which corresponds with the fair value of the whole company. The value, which the whole business is worth, taking into consideration its net income, current bonds yield, level of risk of the business, perspective of the business etc.. The analyst thinks the price will sooner or later hit the target level (if the price is high, investors will exit stocks, if the price is cheap, investors will jump in), but no one knows, how much time will it take." "I think the first misconception to clear up is that you are implying the price of a stock is set by a specific person. It is not. The price of a stock is equal to the value that someone most recently traded at. If Apple last traded at $100/share, then Apple shares are worth $100. If good news about Apple hits the market and people holding the shares ask for more money, and the most recent trade becomes $105, then that is now what Apple shares are worth. Remember that generally speaking, the company itself does not sell you its shares - instead, some other investor sells you shares they already own. When a company sells you shares, it is called a 'public offering'. To get to your actual question, saying something is 'priced in' implies that the 'market' (that is, investors who are buying and selling shares in the company) has already considered the impacts of that something. For example, if you open up your newspaper and read an article about IBM inventing a new type of computer chip, you might want to invest in IBM. But, the rest of the market has also heard the news. So everyone else has already traded IBM assuming that this new chip would be made. That means when you buy, even if sales later go up because of the new chip, those sales were already considered by the person who chose the price to sell you the shares at. One principle of the stock market (not agreed to by all) is called market efficiency. Generally, if there were perfect market efficiency, then every piece of public information about a company would be perfectly integrated into its stock price. In such a scenario, the only way to get real value when buying a company would be to have secret information of some sort. It would mean that everyone's collective best-guess about what will happen to the company has been ""priced-in"" to the most recent share trade."