If I own x% of company A, and A buys company B, do I own x% of B?
No, thanks to the principle of corporate personhood.  The legal entity (company C) is the owner and parent of the private company (sub S).  You and C are separate legal entities, as are C and S. This principle helps to legally insulate the parties for purposes such as liability, torts, taxes, and so forth.  If company C is sued, you may be financially at stake (i.e. your investment in C is devalued or made worthless) but you are not personally being sued.  However, the litigant may attach you as an additional litigant if the facts of the suit merit it.  But without legal separateness of corporations, then potentially all owners and maybe a number of the employees would be sued any time somebody sued the business - which is messy for companies and messy for litigants.  It's also far cleaner for lenders to lend to  unified business entities rather than a variety of thousands of ever-shifting shareholders. Note that this is a separate analysis that assumes the companies are not treated as partnerships or disregarded entities (tax nothings) for tax purposes, in which case an owner may for some purposes be imputed to own the assets of C.  I've also ignored the consolidated tax return, which would allow C and S to file a type of corporate joint return that for some purposes treats them similarly to common entity. For the simplest variation of your question, the answer is no.  You do not own the assets of a corporation by virtue of owning a few of its shares. Edit:  In light of your edit to include FB and Whatsapp, and the wrinkle about corporate books.  If sub S is 100% owned by company C, then you do not have any inspection rights to S because you are not a shareholder.  You also do not have virtual corporation inspection rights through company C.  However, if a person has inspection rights to company C, and sub S appears on the books and financial records of C, then your C rights will do the job of seeing S information. However, Facebook is a public company, so they will make regular public filings and disclosures that should at least partly cover Whatsapp.  So I hedge and clear my throat by averring that my securities training is limited, but I believe that the SEC filings of a public company will as a practical matter (maybe a matter of law?) moot the inspection rights.  At the very least, I suspect you'd need a proper purpose (under DGCL, for example), to demand the inspection, and they will have already made extensive disclosures that I believe will be presumptively sufficient.  I defer to more experienced securities experts on that question, but I don't believe inspection rights are designed for public companies. Ok, so imagine I own x% of Facebook and Facebook buys WhatsApp, does   this mean I own x% of WhatsApp? Yea definitely , you own x% of Whatsapp assuming Facebook buys 100% of WhatApps which is in this case  How much shares of FaceBook do I need to own to have access to   WhatsApp's books? As WhatsApp is a privately held company by Facebook , Facebook is not obliged to reveal the books of WhatsApp , though some not all of the books of WhatsApp may appear in Facebook financial report , it really depends on Facebook Accounting policy.
A buy out is agreed by shareholders. Plus most countries have regulation protecting minority interest. Depending on the terms of buy out, you may get equivalent shares of buyer company or cash or both. "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)." You need to be clear about who gets your money: If you pay the existing owner $25K and (s)he gives you half the business, then you now own half of a $50K business an the original owner has an extra $25K in spending cash.  The value of the business has not changed. If you contribute $25 to the company, new equity shares are created.  Shares should be priced correctly, meaning you now own $25K worth of shares in a company worth $75k, so you should have 1/3 of the outstanding shares (counting both old and new shares).  If you get more or less than this, then the transaction has happened in an unfair way. If this is a public company, that would most likely be illegal and the SEC may throw you in jail.  If it was a private company and your friend created enough shares that you own half the company, then (s)he has given you a gift. If you are contributing to the company at a fair price, you would need to contribute $50K in order to end up with half the equity of the new and now more valuable firm. In that case the firm would be worth $100K after your contribution. Bottom line, this is a common and not complex transaction and should end up with a completely fair outcome.  Any unfair situation you can imagine is probably based on false assumptions or a situation where a non-arms-length transaction is transferring wealth contrary to normal rules and procedures. It depends. If the investor bought newly-issued shares or treasury shares, the company gets the money. If the investor bought shares already held by the owner, the owner gets the money. A 100% owner can decide how to structure the sale. Yet, the investor may only be willing to buy shares if the funds increase the company's working capital. I almost agree. I am not completely sure about the ownership of stock, but to have the majority ownership of any company you must own more than 50% of a company's outstanding shares. Although a board in majority, could out vote a majority shareholder in most cases depending on the company policy regarding shareholders and the general law of the country, and to how the company is managed. Get involved a lawyer and Accountant. Without it you may not be sure what you are getting. What exactly will 30% mean for me? It will mean exactly what gets written in contract. It can mean you are owner of 30% of the company. If this is structured as partnership, it would also mean you are party to 30% loss. It can mean by current valuation, you get x fixed shares. In future if the directors creates more shares, your % ownership can get diluted. Or anything else. It all depends on what is written in contract and how the contract is structured. Is there anything I should I be aware of before agreeing? Get a draft and talk to a Lawyer and Accountant, they should be able to tell you exactly what it means and you can then decide if you agree to it or not; or need this contract worded differently. I agree with the other comments that you should not buy/hold your company stock even if given at a discount. If equity is provided as part of the compensation package (Options/Restrictive Stock Units RSU)then this rule does not apply. As a matter of diversification, you should not have majority equity stake of other companies in the same sector (e.g. technology) as your employer. Asset allocation and diversification if done in the right way, takes care of the returns. Buying and selling on the same day is generally not allowed for ESPP. Taxation headaches. This is from personal experience (Cisco Systems). I had options issued in Sept 2008 at 18$ which vested regularly. I exited at various points - 19$,20$,21$,23$ My friend held on to all of it hoping for 30$ is stuck. Options expire if you leave your employment. ESPP shares though remain. Open Google finance and divide the Market Capitalization by the total price. That will give you the total number of shares outstanding. Now see the number of shares you could buy for $1000(40 shares of $25 each or 10 shares of 100 shares each). Now divide the number of shares you own, by the number of shares outstanding in the company and multiply it by 100(i.e (Shares you own/shares Outstanding) * 100). That will give you the percentage or stake of the company you own(With $1000, don't expect it to be a very large number). Now ask your self the question, Is it worth it if I can buy x % of this company for $1000? If the answer is yes, go ahead and buy it.  To answer your question in short, NO! it does not matter whether you buy 10 shares for $100 or 40 shares for $25. Cheers "As an owner of a share of a business you also ""own"" profits made by the business. But you delegate company management to reinvest those profits, on your behalf, to make even more profits. So your share of the business is a little money-making machine that should grow, without you having to pay taxes on the dividends and without you having to decide where to reinvest your share of the profit." "The first 3 are the same as owning stock in a company would be measured in shares and would constitute some percentage of the overall shares outstanding. If there are 100 shares in the company in total, then owning 80 shares is owning 80% is the same as owning 80% of the common stock. This would be the typical ownership case though there can also be ""Restricted stock"" as something to note here. Convertible debt would likely carry interest charges as well as the choice at the end of becoming stock in the company. In this case, until the conversion is done, the stock isn't issued and thus isn't counted. Taking the above example, one could have a note that could be worth 10 shares but until the conversion is done, the debt is still debt. Some convertible debt could carry options or warrants for the underlying stock as there was the Berkshire convertible notes years ago that carried a negative interest rate that was studied in ""The Negative Coupon Bond"" if you want an example here. Options would have the right but not the obligation to buy the stock where there are ""Incentive Stock Options"" to research this in more depth. In this case, one could choose to not exercise the option and thus no stock changes hands. This is where some companies will experience dilution of ownership as employees and management may be given options that put more shares out to the public. Issuing debt wouldn't change the ownership and isn't direct ownership unless the company goes through a restructuring where the creditors become the new stock holders in the case of a Chapter 11 situation in the US. Note that this isn't really investing in a small business as much as it is making a loan to the company that will be paid back in cash. If the company runs into problems then the creditor could try to pursue the assets of the company to be repaid." First, the stock does represent a share of ownership and if you have a different interpretation I'd like to see proof of that. Secondly, when the IPO or secondary offering happened that put those shares into the market int he first place, the company did receive proceeds from selling those shares. While others may profit afterward, it is worth noting that more than a few companies will have secondary offerings, convertible debt, incentive stock options and restricted stock that may be used down the road that are all dependent upon the current trading share price in terms of how useful these can be used to fund operations, pay executives and so forth. Third, if someone buys up enough shares of the company then they gain control of the company which while you aren't mentioning this case, it is something to note as some individuals buy stock so that they can take over the company which happens. Usually this has more of an overall plan but the idea here is that getting that 50%+1 control of the company's voting shares are an important piece to things here. "Note that these used to be a single ""common"" share that has ""split"" (actually a ""special dividend"" but effectively a split). If you owned one share of Google before the split, you had one share giving you X worth of equity in the company and 1 vote. After the split you have two shares giving you the same X worth of equity and 1 vote. In other words, zero change. Buy or sell either depending on how much you value the vote and how much you think others will pay (or not) for that vote in the future.  As Google issues new shares, it'll likely issue more of the new non-voting shares meaning dilution of equity but not dilution of voting power. For most of us, our few votes count for nothing so evaluate this as you will.  Google's founders believe they can do a better job running the company long-term when there are fewer pressures from outside holders who may have only short-term interests in mind. If you disagree, or if you are only interested in the short-term, you probably shouldn't be an owner of Google. As always, evaluate the facts for yourself, your situation, and your beliefs." "Many thanks for thedetailed  response, appreciate it. But I am still not clear on the distinction between a public company and the equity holders. Isn't a public company = shareholders + equity holders? Or do you mean ""company"" = shareholders+equity holders + debt holders?" "Companies normally do not give you X% of shares, but in effect give you a fixed ""N"" number of shares. The ""N"" may translate initially to X%, but this can go down. If say we began with 100 shares, A holding 50 shares and B holding 50 shares. As the startup grows, there is need for more money. Create 50 more shares and sell it at an arranged price to investor C. Now the percentage of each investor is 33.33%. The money that comes in will go to the company and not to A & B.   From here on, A & C together can decide to slowly cut out B by, for example: After any of the above the % of shares held by B would definitely go down." "Owning more than 50%  of a company's stock normally gives you the right to elect a majority, or even all of a company's (board of) directors. Once you have your directors in place, you can tell them who to hire and fire among managers. There are some things that may stand in the way of your doing this. First, there may be a company bylaw that says that the directors can be replaced only one ""class"" at a time, with three or four ""classes."" Then it could take you two or three years to get control of the company. Second, there may be different classes of shares with different voting rights, so if e.g. ""A"" shares controlled by the founding family gives them ten votes, and ""B"" shares owned by the other shareholders, you may have a majority of total shares and be outvoted by the ""A"" shares."