Why is it important to research a stock before buying it?
The only sensible reason to invest in individual stocks is if you have reason to think that they will perform better than the market as a whole. How are you to come to that conclusion other than by doing in-depth research into the stock and the company behind it?   If you can't, or don't want to, reach that conclusion about particular stocks then you're better off putting your money into cheap index trackers. "The following is only an overview and does not contain all of the in-depth reasons why you should look more deeply. When you look at a stock's financials in depth you are looking for warning signs. These may warn of many things but one important thing to look for is ratio  and growth rate manipulation. Using several different accounting methods it is possible to make a final report reflect a PE ratio (or any other ratio) that is inconsistent with the realities of the company's position. Earnings manipulation (in the way that Enron in particular manipulated them) is more widespread than you might think as ""earnings smoothing"" is a common way of keeping earnings in line (or smooth) in a recession or a boom. The reason that PE ratio looks so good could well be because professional investors have avoided the stock as there appear to be ""interesting"" (but legal) accounting decisions that are of concern. Another issue that you don't consider is growth. earnings may look good in the current reporting period but may have been stagnant or falling when considered over multiple periods. The low price may indicate falling revenues, earnings and market share that you would not be aware of when taking only your criteria into account. Understanding a firm will also give you an insight into how future news might affect the company. If the company has a lot of debt and market interest rates rise or fall how will that effect their debt, if another company brings out a competing product next week how will it effect the company? How will it effect their bottom line? How much do they rely on a single product line? How likely is it that their flagship product will become obsolete? How would that effect the company? Looking deeply into a company's financial statements will allow you to see any issues in their accounting practices and give you a feel for how they are preforming over time, it will also let you look into their cost of capital and investment decisions. Looking deeply into their products, company structure and how news will effect them will give you an understanding of potential issues that could threaten your investment before they occur. When looking for value you shouldn't just look at part of the value of the company; you wouldn't just look at sales of a single T-shirt range at Wallmart when deciding whether to invest in them. It is exactly the same argument for why you should look at the whole of the company's state when choosing to invest rather than a few small metrics." "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""." "Most markets around the world have been downtrending for the last 6 to 10 months. The definition of a downtrend is lower lows and lower highs, and until you get a higher low and confirmation with a higher high the downtrend will continue. If you look at the weekly charts of most indexes you can determine the longer term trend. If you are more concerned with the medium term trend then you could look at the daily charts. So if your objective is to try and buy individual stocks and try to make some medium to short term profits from them I would start by first looking at the daily charts of the index your stock belongs to. Only buy when the intermediate trend of the market is moving up (higher highs and higher lows).  You can do some brief analysis on the stocks your interested in buying, and two things I would add to the short list in your question would be to check if earnings are increasing year after year. The second thing to look at would be to check if the earnings yield is greater than the dividend yield, that way you know that dividends are being paid out from current earnings and not from previous earning or from borrowings. You could then check the daily charts of these individual stocks and make sure they are uptrending also. Buy uptrending stocks in an uptrending market. Before you buy anything write up a trading plan and develop your trading rules. For example if price breaks through the resistance line of a previous high you will buy at the open of the next day. Have your money management and risk management rules in place and stick to your plan. You can also do some backtesting or paper trading to check the validity of your strategy. A good book to read on money and risk management is - ""Trade your way to Financial Freedom"" by Van Tharp. Your aim should not be to get a winner on every trade but to let your winners run and keep your losses small."
Keep a diary, before buying write down why are you buying the stock, how long do you plan to keep it. Put down reasons when you would sell it. For example you buy a stock because it has lot of cash reserve, it is a focused company, good management. You would sell when management leaves or it starts to use its cash for  acquisition that are not fitting in profile. "For starting with zero knowledge you certainly did a great job on research as you hit on most of the important points with your question.  It seems like you have already saved up around six months of expenses in savings so it is a great time to look into investing. The hardest part of your question is actually one of the most important details.  Investing in a way that minimizes your taxes is generally more important, in the end, than what assets you actually invest in (as long as you invest even semi-reasonably).  The problem is that the interaction between your home country's tax system and the U.S. tax system can be complex.  It's probably (likely?) still worth maxing out your 401(k) (IRA, SEP, 529 accounts if you qualify) to avoid taxes, but like this question from an Indian investor it may be worth seeing an investment professional about this.  If you do, see a fee-based professional preferably one familiar with your country.   If tax-advantaged accounts are not a good deal for you or if you max them out, a discount broker is probably a good second option for someone willing to do a bit of research like you. With this money investing in broadly-diversified, low fee, index mutual funds or exchange traded funds is generally recommended.  Among other benefits, diversified funds make sure that if any particular company fails you don't feel too much pain.  The advantages of low fees are fairly obvious and one very good reason why so many people recommend Vanguard on this site.  A common mix for someone your age is mostly stocks (local and international) and some bonds.  Though with how you talk about risk you may prefer more bonds. Some people recommend spicing this up a bit with a small amount of real estate (REITs), sometimes even other assets.  The right portfolio of the above can change a lot given the person.  The above mentioned adviser and/or more research can help here. If, in the future, you start to believe you will go back to your home country soon that may throw much of this advice out the window and you should definitely reevaluate then.  Also, if you are interested in the math/stats behind the above advice ""A Random Walk Down Wall Street"" is a light read and a good place to start.  Investing makes for a very interesting and reasonably profitable math/stats problem." "To add on to the other answers, in asking why funds have different price points one might be asking why stocks aren't normalized so a unit price of $196 in one stock can be directly compared to the same price in another stock.  While this might not make sense with AAPL vs. GOOG (it would be like comparing apples to oranges, pun intended, not to mention how would two different companies ever come to such an agreement) it does seem like it would make more sense when tracking an index.  And in fact less agreement between different funds would be required as some ""natural"" price points exist such as dividing by 100 (like some S&P funds do). However, there are a couple of reasons why two different funds might price their shares of the same underlying index differently. Demand - If there are a lot of people wanting the issue, more shares might be issued at a lower price.  Or, there might be a lot of demand centered on a certain price range. Pricing - shares that are priced higher will find fewer buyers, because it makes it harder to buy round lots (100 shares at $100/share is $10,000 while at $10/share it's only $1000).  While not everyone buys stock in lots, it's important if you do anything with (standardized) options on the stock because they are always acting on lots.  In addition, even if you don't buy round lots a higher price makes it harder to buy in for a specific amount because each unit share has a greater chance to be further away from your target amount. Conversely, shares that are priced too low will also find fewer buyers, because some holders have minimum price requirements due to low price (e.g. penny) stocks tending to be more speculative and volatile. So, different funds tracking the same index might pick different price points to satisfy demand that is not being filled by other funds selling at a different price point." To expand a bit on what TripeHound said in the comment section, past performance is not indicative of future performance, which is why the best advice is to ignore if you already own the stock or not.  If the stock goes down, but you've done your research and think it will come back, then investing more isn't a bad idea. If the stock is doing well and it will continue to do well, then invest more. Treat investing more into a stock you already own as a new investment and do your research.  TL;DR of your question, it's a very case-by-case basis Investing in the stock market early is a good thing.  However, it does have a learning curve, and that curve can, and eventually will, cost you. One basic rule in investing is that risk and reward are proportional.  The greater the reward, the higher the risk that you either (a) won't get the reward, or (b) lose your money instead.  Given that, don't invest money you can't afford to lose (you mentioned you're on a student budget). If you want to start with short but sercure investments, try finding a high-interest savings account or CD.  For example, the bank I use has an offer where the first $500 in your account gets ~6% interest - certainly not bad if you only put $500 in the account.  Unfortunately, most banks are offering a pittance for savings rates or CDs. If you're willing to take more risk, you could certainly put money into the stock market.  Before you do, I would recommend spending some time learning about how the stock market works, it's flows and ebbs, and how stock valuations work.  Don't buy a stock because you hear about it a lot; understand why that stock is being valued as such.  Also consider buying index funds (such as SPY) which is like a stock but tracks an entire index.  That way if a specific company suddenly drops, you won't be nearly as affected.  On the flip side, if only 1 company goes up, but the market goes down, you'll miss out.  But consider the odds of having picked that 1 company. "A share of stock is a share of the underlying business. If one believes the underlying business will grow in value, then one would expect the stock price to increase commensurately. Participants in the stock market, in theory, assign value based on some combination of factors like capital assets, cash on hand, revenue, cash flow, profits, dividends paid, and a bunch of other things, including ""intangibles"" like customer loyalty. A dividend stream may be more important to one investor than another. But, essentially, non-dividend paying companies (and, thus, their shares) are expected by their owners to become more valuable over time, at which point they may be sold for a profit. EDIT TO ADD: Let's take an extremely simple example of company valuation: book value, or the sum of assets (capital, cash, etc) and liabilities (debt, etc). Suppose our company has a book value of $1M today, and has 1 million shares outstanding, and so each share is priced at $1. Now, suppose the company, over the next year, puts another $1M in the bank through its profitable operation. Now, the book value is $2/share. Suppose further that the stock price did not go up, so the market capitalization is still $1M, but the underlying asset is worth $2M. Some extremely rational market participant should then immediately use his $1M to buy up all the shares of the company for $1M and sell the underlying assets for their $2M value, for an instant profit of 100%. But this rarely happens, because the existing shareholders are also rational, can read the balance sheet, and refuse to sell their shares unless they get something a lot closer to $2--likely even more if they expect the company to keep getting bigger. In reality, the valuation of shares is obviously much more complicated, but this is the essence of it. This is how one makes money from growth (as opposed to income) stocks. You are correct that you get no income stream while you hold the asset. But you do get money from selling, eventually." When you buy a stock, the worst case scenario is that it drops to 0.  Therefore, the most you can lose when buying a stock is 100% of your investment. When you short a stock, however, there's no limit on how high the stock can go.  If you short a stock at 10, and it goes up to 30, then you've lost 200% on your investment.  Therefore shorting stocks is riskier than buying stocks, since you can lose more than 100% of your investment when shorting. because the price might go up, but it will never be as big of a change as a regular price drop i suppose... That is not true.  Stocks can sometimes go up significantly (50-100% or more) in a very short amount of time on a positive news release (such as an earnings or a buyout announcement).  A famous example occurred in 2008, when Volkswagen stock quintupled (went up 400%) in less than 2 days on some corporate news: Porsche, for some reason, wants to control Volkswagen, and by building up its stake has driven up the price. Hedge funds, figuring the share price would fall as soon as Porsche got control and stopped buying, sold a lot of VW shares short. Then last weekend, Porsche disclosed that it owned 42.6 percent of the stock and had acquired options for another 31.5 percent. It said it wanted to go to 75 percent. The result: instant short-squeeze. The German state of Lower Saxony owns a 20 percent stake in VW, which it said it would not sell. That left precious few shares available for anyone else. The shorts scrambled to cover, and the price leaped from about €200, or about $265, to above €1,000. according to me it's the news about a particular stock which makes people to buy or sell it mostly thus creates a fluctuation in price . It also dependents on the major stock holder.