How meaningful is the “stock price” of a stock?
Prices quoted are primarily the offer prices quoted by the numerous market makers on the stock exchange(s) willing to sell you the stock. There is another price which generally isn't seen on these websites, the bid prices, which are lower prices quoted by buyers and market makers willing to buy your shares from you. You wouldn't see those prices, unless you login to your trade terminal. How meaningful are they to you depends on what you want to do buy or sell. If you want to buy then yes they are relevant. But if you want to sell, then no. And remember some websites delay market information by 15 minutes, in case of Google you might have seen that the volume is delayed by 15 minutes. So you need to consider that also while trading, but mayn't be a concern unless you are trying to buy out the company. The information on GOOG or other sites is the average price of the stock and is indicative of the price at with the stock would be available. The actual trades happen at different values throught the day ...  So the prices are good for most purposes and if you need the exact prices, you can thne decided to log into you trading terminal and get the actual quotes   This is similar to FX quotes or any other such quotes and give you a general sense
The Sharpe ratio is, perhaps, the method you are looking for.  That said, not really sure beta is a meaningful metric, as there are plenty of safe bets to be made on volatile stocks (and, conversely, unsafe bets to be made on non-volatile ones). "Yes, you could buy a stock on the day of its IPO. I'm a college student, and I wonder if I can buy stock from a company   right after it finishes its IPO? Yes, you can. However, unless you are friends or family of an employee, chances are you'll be paying a higher price than you think as there is generally a fair bit of hype on most  IPOs that allows some people to ""flip them"" which means someone is buying at a higher price. If I am not allowed to buy its stocks immediately after they go on   sell, how long do I have to wait? Generally I'd wait until the hype dies down as if you look at most historical IPOs the stock could be bought cheaper later but that's just my perspective. And also who are allowed to buy the stocks at the first minute they   are on sell? Anyone but keep in mind that while an IPO may be priced at $x, the initial trades may be a few times that value and the stock may come down over time. Facebook could be an example to consider of a company that had an IPO at one price and then came down for a little while on its chart over the past couple of years." The main question is, how much money you want to make?  With every transaction, you  should calculate the real price as the price plus costs. For example, if you but 10 GreatCorp stock of £100 each, and the transaction cost is £20 , then the real cost of buying a single share is in fact buying price of stock + broker costs / amount bought, or £104 in this case.  Now you want to make a profit so calculate your desired profit margin. You want to receive a sales price of buying price + profit margin + broker costs / amount bought. Suppose that you'd like 5%, then you'll need the price per stock of my example to increase to 100 + 5% + £40 / 10 = £109.  So you it only becomes worth while if you feel confident that GreatCorp's stock  will rise to that level. Read the yearly balance of that company to see if they don't have any debt, and are profitable. Look at their dividend earning history. Study the stock's candle graphs of the last ten years or so, to find out if there's no seasonal effects, and if the stock performs well overall. Get to know the company well. You should only buy GreatCorp shares after doing your homework.  But what about switching to another stock of LovelyInc? Actually it doesn't matter, since it's best to separate transactions. Sell your GreatCorp's stock when it has reached the desired profit margin or if it seems it is underperforming. Cut your losses! Make the calculations for LovelyCorp's shares without reference to GreatCorp's, and decide like that if it's worth while to buy. What are the risks pertaining to timing on long term index   investments? The risks are countless for any investment strategy.  If you invest in US stocks, and prices revert to the long term cyclically adjusted average, you will lose a lot of money.  If you invest in cash, inflation may outpace interest rates and you will lose money.  If you invest in gold, the price might go down and you will lose money.  It's best to study history and make a reasonable decision (i.e. invest in stocks). Here are long term returns by asset class, computed by Jeremy Siegel:  $1 invested in equities in 1801 equals $15.22 today if was not invested and $8.8 million if it was invested in stocks.  This is the 'magic of compound interest' and cash / bonds have not been nearly as magical as stocks historically. 2) How large are these risks? The following chart shows the largest drawdowns (decreases in the value of an asset) since 1970 (source):  Asset prices decrease in value frequently.  Financial assets are volatile, but historically, they have increased over time, enabling investors to earn compounded returns (exponential growth of money is how to get rich).  I personally view drawdowns as an excellent time to buy - it's like going on a shopping spree when everything in the store is discounted. 3) In case I feel not prepared to take these risks, how can I avoid   them? The optimal asset allocation depends on the ability to take risk and your tolerance for risk.  You are young and have a long investment horizon, so if stocks go down, you will have plenty of time to wait for them to go back up (if you're smart, you'll buy more stocks when they go down because they're cheap), so your ability to bear risk is high.  From your description, it seems like you have a low risk tolerance (despite a high ability to be exposed to risk).  Here's the return of various asset classes and how the average investor has fared over the last 20 years (source):  Get educated (read Common Sense on Mutual Funds, A Random Walk Down Wall Street, etc.) and don't be average! Closing words: Investing in a globally diversified portfolio with a dollar cost averaging strategy is the best strategy for most investors.  For investors that are unable to stay rational when markets are volatile (i.e. the investor uncontrollably sells their stocks when stocks decrease 20%), a more conservative asset allocation is recommended.  Due to the nature of compounded interest, a conservative portfolio is likely to have a much lower future value. The worth of a share of stocks may be defined as the present cash value of all future dividends and liquidations associated therewith.  Without a crystal ball, such worth may generally only be determined retrospectively, but even though it's generally not possible to know the precise worth of a stock in time for such information to be useful, it has a level of worth which is absolute and not--unlikely market price--is generally unaffected by people buying and selling the stock (except insofar as activities in company stock affect a company's ability to do business). If a particular share of stock is worth $10 by the above measure, but Joe sells it to Larry for $8, that means Joe gives Larry $2.  If Larry sells it to Fred $12, Fred gives Larry $2.  The only way Fred can come out ahead is if he finds someone else to give him $2 or more.  If Fred can sell it to Adam for $13, then Adam will give Fred $3, leaving Fred $1 better off than he would be if he hadn't bought the stock, but Adam will be $3 worse off. The key point is that if you sell something for less than it's worth, or buy something for more that it's worth, you give money away.  You might be able to convince other people to give you money in the same way you gave someone else money, but fundamentally the money has been given away, and it's not coming back. "Ditto to MD-Tech, but from a more ""philosophical"" point of view: When you buy stock, you own it, just like you own a cell phone or a toaster or a pair of socks that you bought. The difference is that a share of stock means that you own a piece of a corporation. You can't physically take possession of it and put it in your garage, because if all the stock-holders did that, then all the company's assets would be scattered around all the stock-holder's garages and the company couldn't function. Like if you bought a 1/11 share in a football team, you couldn't take one of the football players home and keep him in your closet, because then the team wouldn't be able to function. (I might want to take one of the cheerleaders home, but that's another subject ...) In pre-electronic times, you could get a piece of paper that said, ""XYZ Corporation - 1 share"". You could take physical possession of this piece of paper and put it in your filing cabinet. I'm not sure if you can even get such certificates any more; I haven't seen one in decades. These days it's just recorded electronically. That doesn't mean that you don't own it. It just means that someone else is keeping the records for you. It's like leaving your car in a parking lot. It's still your car. The people who run the parking lot doesn't own it. They are keeping it for you, but just because they have physical possession doesn't make it theirs." The company's value (which should be reflected in the share price) is not how much money it has in the bank, but something along the lines of 'how much money will it make between now and the end of times' (adjusted for time value of money and risk). So when you purchase a share of a company that has, say, little money in the bank, but expects to make 1M$ profit this year, 2M$ for the following 3 years, and say, nothing after, you are going to pay your fraction of 7M$ (minus some discount because of the risk involved). If now they announce that their profits were only 750k$, then people may think that the 2M$ are more likely to be 1.5M$, so the company's value would go to ~ 5M$. And with that, the market may perceive the company as more risky, because its profits deviated from what was expected, which in turn may reduce the company's value even further. "A stock, at its most basic, is worth exactly what someone else will pay to buy it right now (or in the near future), just like anything else of value. However, what someone's willing to pay for it is typically based on what the person can get from it. There are a couple of ways to value a stock. The first way is on expected earnings per share, most of would normally (but not always) be paid in dividends. This is a metric that can be calculated based on the most recently reported earnings, and can be estimated based on news about the company or the industry its in (or those of suppliers, likely buyers, etc) to predict future earnings. Let's say the stock price is exactly $100 right now, and you buy one share. In one quarter, the company is expected to pay out $2 per share in dividends. That is a 2% ROI realized in 3 months. If you took that $2 and blew it on... coffee, maybe, or you stuffed it in your mattress, you'd realize a total gain of $8 in one year, or in ROI terms an annual rate of 8%. However, if you reinvested the money, you'd be making money on that money, and would have a little more. You can calculate the exact percentage using the ""future value"" formula. Conversely, if you wanted to know what you should pay, given this level of earnings per share, to realize a given rate of return, you can use the ""present value"" formula. If you wanted a 9% return on your money, you'd pay less for the stock than its current value, all other things being equal. Vice-versa if you were happy with a lesser rate of return. The current rate of return based on stock price and current earnings is what the market as a whole is willing to tolerate. This is how bonds are valued, based on a desired rate of return by the market, and it also works for stocks, with the caveat that the dividends, and what you'll get back at the ""end"", are no longer constant as they are with a bond. Now, in your case, the company doesn't pay dividends. Ever. It simply retains all the earnings it's ever made, reinvesting them into doing new things or more things. By the above method, the rate of return from dividends alone is zero, and so the future value of your investment is whatever you paid for it. People don't like it when the best case for their money is that it just sits there. However, there's another way to think of the stock's value, which is it's more core definition; a share of the company itself. If the company is profitable, and keeps all this profit, then a share of the company equals, in part, a share of that retained earnings. This is very simplistic, but if the company's assets are worth 1 billion dollars, and it has one hundred million shares of stock, each share of stock is worth $10, because that's the value of that fraction of the company as divided up among all outstanding shares. If the company then reports earnings of $100 million, the value of the company is now 1.1 billion, and its stock should go up to $11 per share, because that's the new value of one ten-millionth of the company's value. Your ROI on this stock is $1, in whatever time period the reporting happens (typically quarterly, giving this stock a roughly 4% APY). This is a totally valid way to value stocks and to shop for them; it's very similar to how commodities, for instance gold, are bought and sold. Gold never pays you dividends. Doesn't give you voting rights either. Its value at any given time is solely what someone else will pay to have it. That's just fine with a lot of people right now; gold's currently trading at around $1,700 an ounce, and it's been the biggest moneymaker in our economy since the bottom fell out of the housing market (if you'd bought gold in 2008, you would have more than doubled your money in 4 years; I challenge you to find anything else that's done nearly as well over the same time). In reality, a combination of both of these valuation methods are used to value stocks. If a stock pays dividends, then each person gets money now, but because there's less retained earnings and thus less change in the total asset value of the company, the actual share price doesn't move (much). If a stock doesn't pay dividends, then people only get money when they cash out the actual stock, but if the company is profitable (Apple, BH, etc) then one share should grow in value as the value of that small fraction of the company continues to grow. Both of these are sources of ROI, and both are seen in a company that will both retain some earnings and pay out dividends on the rest."