How did I end up with a fraction of a share?
It's not that uncommon but it doesn't usually come from standard purchases.  Investopedia explains: Definition of 'Fractional Share' A share of equity that is less than one full share. Fractional shares usually come about from stock splits, dividend reinvestment plans (DRIPs) and similar corporate actions. Normally, fractional shares cannot be acquired from the market. However, there is at least one investment firm that markets itself as offering fractional shares.  Fractional investing makes more sense, since an investor's perspective is to invest a certain number of dollars into equity, not to buy a certain number of shares that closely mirror the dollar commitment. Theoretically, yes, you can only buy or sell whole shares (which is why you still have .16 shares in your account; you can't sell that fraction on the open market). This is especially true for voting stock; stock which gives you voting rights in company decisions makes each stock one vote, so effectively whomever controls the majority of one stock gets that vote. However, various stock management policies on the part of the shareholder, brokerage firm or the issuing company can result in you owning fractional shares. Perhaps the most common is a retirement account or other forward-planning account. In such situations, it's the dollar amount that counts; when you deposit money you expect the money to be invested in your chosen mix of mutual funds and other instruments. If the whole-shares rule were absolute, and you wanted to own, for instance, Berkshire Hathaway stock, and you were contributing a few hundred a month, it could take you your entire career of your contributions sitting in a money-market account (essentially earning nothing) before you could buy even one share. You are virtually guaranteed in such situations to end up owning fractions of shares in an investment account. In these situations, it's usually the fund manager's firm that actually holds title to the full share (part of a pool they maintain for exactly this situation), and your fractional ownership percentage is handled purely with accounting; they give you your percentage of the dividends when they're paid out, and marginal additional investments increase your actual holdings of the share until you own the whole thing. If you divest, the firm sells the share of which you owned a fraction (or just holds onto it for the next guy fractionally investing in the stock; no need to pay unnecessary broker fees) and pays you that fraction of the sale price.  Another is dividend reinvestment; the company may indicate that instead of paying a cash dividend, they will pay a stock dividend, or you yourself may indicate to the broker that you want your dividends given to you as shares of stock, which the broker will acquire from the market and place in your account. Other common situations include stock splits that aren't X-for-1. Companies often aren't looking to halve their stock price by offering a two-for-one split; they may think a smaller figure like 50% or even smaller is preferable, to fine tune their stock price (and thus P/E ratio and EPS figures) similar to industry competitors or to companies with similar market capitalization. In such situations they can offer a split that's X-for-Y with X>Y, like a 3-for-2, 5-for-3 or similar. These are relatively uncommon, but they do happen; Home Depot's first stock split, in 1987, was a 3-for-2. Other ratios are rare, and MSFT has only ever been split 2-for-1. So, it's most likely that you ended up with the extra sixth of a share through dividend reinvestment or a broker policy allowing fractional-share investment. Fractional shares don't occur from Dividend Reinvestment Programs - residual credit is carried over until there is enough to purchase a whole share.
As BrenBarn stated, tracking fractional transactions beyond 8 decimal places makes no sense in the context of standard stock and mutual fund transactions.  This is because even for the most expensive equities, those fractional shares would still not be worth whole cent amounts, even for account balances in the hundreds of thousands of dollars. One important thing to remember is that when dealing with equities the total cost, number of shares, and share price are all 3 components of the same value.  Thus if you take 2 of those values, you can always calculate the third: (price * shares = cost, cost / price = shares, etc).  What you're seeing in your account (9 decimal places) is probably the result of dividing uneven values (such as $9.37 invested in a commodity which trades for $235.11, results in 0.03985368550891072264046616477394 shares).  Most brokerages will round this value off somewhere, yours just happens to include more decimal places than your financial software allows. Since your brokerage is the one who has the definitive total for your account balance, the only real solution is to round up or down, whichever keeps your total balance in the software in line with the balance shown online. "You didn't win in case B. Borrowing shares and then selling them is known as ""selling short"".  You received $2000 when you sold short 100 shares at $20.  You spent $1000 to buy them back at $10, so you come out $1000 ahead on that deal.  But at the same time, the 100 shares you already owned have declined in value from $20 to $10, so you are down $1000 on that deal.  So you've simply broken even, and you are still out the interest and transaction fees. In effect, a short sale allows you to sell shares you don't own.  But if you do already own them, then the effect is the same as if you just sold your own shares.  This makes it easier to see that this is just a complicated and expensive way of accomplishing nothing at all." A share is just a part ownership of a company. If you buy a share of a green stock in the open market, you now just own  part of a green company. Just like if you buy a house, the money you paid moves to the former owner, but what you are getting is a clear asset in return that you now own. Via mutual funds/indexes this can get a little more complicated (voting rights etc tend to go to the mutual/indexing company rather than the holders of the fund), but is approximately the same thing: the fund buys assets on the open market, then holds them, buys more, or sells them on behalf of the fund investors. You buy a share of something for $100.  It goes up by 10% over a year, and you now have $110 in value.  It goes up by 10% next year and you now have $121.  That original $10 increase was compounded even though you're not earning interest because the gains are measured as a percentage.  If, instead, you'd only invested the second year you'd have less value.  Assuming the markets average a positive gain (above inflation) you see greater gains the earlier you're invested. "I probably don't understand something. I think you are correct about that.  :) The main way money enters the stock market is through investors investing and taking money out. Money doesn't exactly ""enter"" the stock market.  Shares of stock are bought and sold by investors to investors.  The market is just a mechanism for a buyer and seller to find each other. For the purposes of this question, we will only consider non-dividend stocks. Okay. When you buy stock, it is claimed that you own a small portion of the company. This statement has no backing, as you cannot exchange your stock for the company's assets. For example, if I bought $10 of Apple Stock early on, but it later went up to $399, I can't go to Apple and say ""I own $399 of you, here you go it back, give me an iPhone."" The only way to redeem this is to sell the stock to another investor (like a Ponzi Scheme.) It is true that when you own stock, you own a small portion of the company.  No, you can't just destroy your portion of the company; that wouldn't be fair to the other investors.  But you can very easily sell your portion to another investor.  The stock market facilitates that sale, making it very easy to either sell your shares or buy more shares. It's not a Ponzi scheme.  The only reason your hypothetical share is said to be ""worth"" $399 is that there is a buyer that wants to buy it at $399.  But there is a real company behind the stock, and it is making real money. There are several existing questions that discuss what gives a stock value besides a dividend: The stock market goes up only when more people invest in it. Although the stock market keeps tabs on Businesses, the profits of Businesses do not actually flow into the Stock Market. In particular, if no one puts money in the stock market, it doesn't matter how good the businesses do. The value of a stock is simply what a buyer is willing to pay for it.  You are correct that there is not always a correlation between the price of a stock and how well the company is doing.  But let's look at another hypothetical scenario. Let's say that I started and run a publicly-held company that sells widgets.  The company is doing very well; I'm selling lots of widgets.  In fact, the company is making incredible amounts of money.  However, the stock price is not going up as fast as our revenues.  This could be due to a number of reasons: investors might not be aware of our success, or investors might not think our success is sustainable.  I, as the founder, own lots of shares myself, and if I want a return on my investment, I can do a couple of things with the large revenues of the company: I can either continue to reinvest revenue in the company, growing the company even more (in the hopes that investors will start to notice and the stock price will rise), or I can start paying a dividend.  Either way, all the current stock holders benefit from the success of the company." As a start-up, the initial shares can be given at various price points. So essentially they can give someone a larger percentage based on the same amount earlier, and lesser percentage to someone else for the same amount. As its a start-up the valuations can be very tricy and what matters is that whether you believe the percentage you got for the amount is right or not.   It is very important to note that when you have been given an ownership in the company, how that is designated. Is it in absolute number of shares or is it in terms of percentage based on the existing shares. For example you maybe given 100 shares, without any qualification. Or you maybe given a 5% stake in the paid-up capital, that translates to 100 shares. It is always better to hold the shares in % of the total shares. Also read the contract, any dilution should require your approval. Normally start-ups once the valuation starts to go up, start creating more shares and sell these to private equity or create more shares and give it as a bonus to promoters. Hence in both cases your holding will keep getting diluted. There is a related quesiton If a startup can always issue new shares, what value is there to stocks/options? This answer contains three assumptions: New Share Price: Old Share Price * 1.0125 Quarterly Dividend: (New Share Price*0.01) * # of Shares in Previous Quarter Number of Shares: Shares from Previous Quarter + Quarterly Dividend/New Share Price For example, starting from right after Quarter One: New share price: $20 * 1.0125 = 20.25  1000 shares @ $20.25 a share yields $20.25 * 0.01 * 1000 = $202.5 dividend New shares: $202.5/20.25 = 10 shares Quarter Two: New share price: $20.503 1010 shares @ 20.503 yields $20.503*0.01*1010 = $207.082 dividend New shares: $207.082/20.503 = 10.1 shares Repeat over many cycles: 8 Quarters (2 years): 1061.52 shares @ $21.548 a share 20 Quarters (5 years): 1196.15 shares @ $25.012 a share 40 Quarters (10 years): 1459.53 shares @ $32.066 a share Graphically this looks like this:  It's late enough someone may want to check my math ;). But I'd also assert that a 5% growth rate and a 4% dividend rate is pretty optimistic. You can become an activist share holder with as little as one share depending on your strategy an example of this was Hugh Fearnley-Whittingstall (excellent name) vs Tesco (a huge supermarket, think walmart). He purchased one share which gave him the right to table a resolution at the AGM, then used the media to beat Tesco into submission over his particular issue however very few of the institution share holders (think large banks, pension funds, insurance companies) voted in favor so he failed miserably, but Tesco later caved slightly through fear of bad press. Also Carl Icahn is pretty well noted for doing things like this.  Regarding the amount of money, you would need to raise a hell of a lot to buy enough shares to have anything like enough of a block to influence the company directly, but to attend the AGM, ask questions and generally be a pain in the ass you only need modest amount of shares, in some cases just one share. Thank you for replying. I'm not sure I totally follow though, aren't you totally at mercy of the liquidity in the stock? I guess I'm havinga hard time visualizing the value a human can add as opposed to say vwapping it or something. I can accept that you're right, just having a difficult time picturing it You or the broker place an order to buy the share with the stock exchange. There has to be a matching sell order by someone.  Once a match is made, you pay the money and get the share. Let me answer with an extreme example - I own the one single share of a company, and it's worth $1M. I issue 9 more shares, and find 9 people willing to pay $1M for each share. I know find my ownership dropped by 90%, and I am now a 10% owner of a business that was valued at $1M but with an additional $9M in the bank for expansion. (Total value now $10M) Obviously, this is a simplistic view, but no simpler than the suggestion that your company would dilute its shares 90% in one transaction. "None of that is filtered my way as a ""part owner"". Sure it is, it's just not always obvious. When a company makes money it either: Other then the fourth option, the first three all increase the total value of the company.  If you owned 1% of a company that was worth X, and is now worth X+1, the value of that 1% ownership should go up as well. One model of the value of a share of stock is the present value of all future cash flows that the company produces for its shareholders, which would be either through dividends, earnings (provided that they are invested back into the company) or through liquidation (sale).  So as earnings increase (or more accurately as projected future earnings increase), so does the value of a share of the company. Also note that the payment of dividends causes the price of a stock to go down when the dividend is paid, since that's equity (cash) that's leaving the company, reducing the value of the company by an equivalent amount. Of course, there's also something to be said for the behavioral aspect of investing, meaning that people sometimes invest in companies that they like, and sell stock of companies that they don't like or disagree with (e.g. Nordstrom's)." Well, if one share cost $100 and the company needs to raise $10000, then the company will issue 100 shares for that price.  Right? However, say there's 100 shares out there now, then each share holder owns 1/100th of the company. Now the company will remain the same, but it's shared between 200 shareholders after the issuing of new shares.  That means each share holder now owns 1/200th of the company.  And hence only gets 1/200th of their earnings etc. Okay I don't know where my disconnect was, in my mind I was viewing that as a negative for some reason haha. Thanks! That makes sense.  What is your perspective on the large amount of companies buying back shares right now? You're wise to consider mitigating risks considering your age and portfolio size, but 'in' and 'out' are so reductive and binary. Why not be both? Leave some in and let it ride, providing growth but taking risk. Put some in bonds, where it'll earn more than cash and maybe zig when stocks zag. I applaud you for calling the last two crashes, but remember: a lot of people called them. Jeremy Bentham called the dot com bubble *years* in advance - of course, he got out too early, and the investors in his funds suffered for it. Timing means getting the sell and the buy right, which very few can do. Hence my advice to hold a balanced portfolio or *if you really do have the golden touch* make use of that ability and get rich - no need to work a 9 to 5 if you can call market crashes accurately.