By the American Revolution, Spanish dollars gained significance because they backed paper money authorized by the individual colonies and the Continental Congress.[4] Common in the Thirteen Colonies, Spanish dollars were even legal tender in one colony, Virginia.

On April 2, 1792, U. S. Secretary of the Treasury Alexander Hamilton reported to Congress the precise amount of silver found in Spanish milled dollar coins in common use in the States. As a result, the United States dollar was defined[12] as a unit of weight equaling 371 4/16th grains (24.057 grams) of pure silver, or 416 grains of standard silver (standard silver being defined as 1,485 parts fine silver to 179 parts alloy).[13] It was specified that the "money of account" of the United States should be expressed in those same "dollars" or parts thereof. Additionally, all lesser-denomination coins were defined as percentages of the dollar coin, such that a half-dollar was to contain half as much silver as a dollar, quarter-dollars would contain one-fourth as much, and so on.

In an act passed in January 1837, the dollar's alloy (amount of non-silver metal present) was set at 15%. Subsequent coins would contain the same amount of pure silver as previously, but were reduced in overall weight (to 412.25 grains). On February 21, 1853, the quantity of silver in the lesser coins was reduced, with the effect that their denominations no longer represented their silver content relative to dollar coins.

Various acts have subsequently been passed affecting the amount and type of metal in U. S. coins, so that today there is no legal definition of the term "dollar" to be found in U. S. statute.[14][15][16] Currently the closest thing to a definition is found in United States Code Title 31, Section 5116, paragraph b, subsection 2: "The Secretary [of the Treasury] shall sell silver under conditions the Secretary considers appropriate for at least $1.292929292 a fine troy ounce."

Silver was mostly removed from U. S. coinage by 1965 and the dollar became a free-floating fiat currency without a commodity backing defined in terms of real gold or silver. The US Mint continues to make silver $1-denomination coins, but these are not intended for general circulation

In finance, short selling (also known as shorting or going short) is the practice of selling assets, usually securities, that have been borrowed from a third party (usually a broker) with the intention of buying identical assets back at a later date to return to that third party. The basic principle followed is that selling something high now, to buy lower later, is profitable. The short seller hopes to profit from a decline in the price of the assets between the sale and the repurchase, as the seller will pay less to buy the assets than it received on selling them. The short seller will incur a loss if the price of the assets rises (as it will have to buy them at a higher price than it sold them), and the loss that can be incurred by a short seller is only limited by the total strike price. Other costs of shorting may include a fee for borrowing the assets and payment of any dividends paid on the borrowed assets. "Shorting" and "going short" also refer to entering into any derivative or other contract under which the investor similarly profits from a fall in the value of an asset. Mathematically, short selling is equivalent to buying a negative amount of the assets.

Short selling is almost always conducted with assets traded in public securities, commodities or currency markets, as on such markets the amount being made or lost can be monitored in real time and it is generally possible to buy back the borrowed assets whenever required. Because such assets are fungible, any assets of the same type bought on those markets can be used to return to the lender.

Going short can be contrasted with the more conventional practice of "going long", whereby an investor profits from any increase in the price of the asset.

Shareholder rights

Although ownership of 50% of shares does result in 50% ownership of a company, it does not give the shareholder the right to use a company's building, equipment, materials, or other property. This is because the company is considered a legal person, thus it owns all its assets itself. This is important in areas such as insurance, which must be in the name of the company and not the main shareholder.

In most countries, boards of directors and company managers have a fiduciary responsibility to run the company in the interests of its stockholders. Nonetheless, as Martin Whitman writes:
...it can safely be stated that there does not exist any publicly traded company where management works exclusively in the best interests of OPMI [Outside Passive Minority Investor] stockholders. Instead, there are both "communities of interest" and "conflicts of interest" between stockholders (principal) and management (agent). This conflict is referred to as the principal/agent problem. It would be naive to think that any management would forego management compensation, and management entrenchment, just because some of these management privileges might be perceived as giving rise to a conflict of interest with OPMIs.[14]
Even though the board of directors runs the company, the shareholder has some impact on the company's policy, as the shareholders elect the board of directors. Each shareholder typically has a percentage of votes equal to the percentage of shares he or she owns. So as long as the shareholders agree that the management (agent) are performing poorly they can elect a new board of directors which can then hire a new management team. In practice, however, genuinely contested board elections are rare. Board candidates are usually nominated by insiders or by the board of the directors themselves, and a considerable amount of stock is held or voted by insiders.

Owning shares does not mean responsibility for liabilities. If a company goes broke and has to default on loans, the shareholders are not liable in any way. However, all money obtained by converting assets into cash will be used to repay loans and other debts first, so that shareholders cannot receive any money unless and until creditors have been paid (often the shareholders end up with nothing).[15]

[edit] Means of financing

Financing a company through the sale of stock in a company is known as equity financing. Alternatively, debt financing (for example issuing bonds) can be done to avoid giving up shares of ownership of the company. Unofficial financing known as trade financing usually provides the major part of a company's working capital (day-to-day operational needs).

[edit] Trading

Main article: Stock trader

In general, the shares of a company may be transferred from shareholders to other parties by sale or other mechanisms, unless prohibited. Most jurisdictions have established laws and regulations governing such transfers, particularly if the issuer is a publicly-traded entity.

The desire of stockholders to trade their shares has led to the establishment of stock exchanges, organizations which provide marketplaces for trading shares and other derivatives and financial products. Today, stock traders are usually represented by a stock broker who buys and sells shares of a wide range of companies on such exchanges. A company may list its shares on an exchange by meeting and maintaining the listing requirements of a particular stock exchange. In the United States, through the intermarket trading system, stocks listed on one exchange can often also be traded on other participating exchanges, including electronic communication networks (ECNs), such as Archipelago or Instinet.[16]

Many large non-U.S companies choose to list on a U.S. exchange as well as an exchange in their home country in order to broaden their investor base. These companies must maintain a block of shares at a bank in the US, typically a certain percentage of their capital. On this basis, the holding bank establishes American depositary shares and issues an American depositary receipt (ADR) for each share a trader acquires. Likewise, many large U.S. companies list their shares at foreign exchanges to raise capital abroad.

Small companies that do not qualify and cannot meet the listing requirements of the major exchanges may be traded over-the-counter (OTC) by an off-exchange mechanism in which trading occurs directly between parties. The major OTC markets in the United States are the electronic quotation systems OTC Bulletin Board (OTCBB) and OTC Markets Group where individual retail investors are also represented by a brokerage firm and the quotation service's requirements for a company to be listed are minimal. Shares of companies in bankruptcy proceeding are usually listed by these quotation services after the stock is delisted from an exchange.

Buying

There are various methods of buying and financing stocks, the most common being through a stock broker. Whether they are a full service or discount broker, they arrange the transfer of stock from a seller to a buyer. Most trades are actually done through brokers listed with a stock exchange.

There are many different stock brokers from which to choose, such as full service brokers or discount brokers. The full service brokers usually charge more per trade, but give investment advice or more personal service; the discount brokers offer little or no investment advice but charge less for trades. Another type of broker would be a bank or credit union that may have a deal set up with either a full service or discount broker.

There are other ways of buying stock besides through a broker. One way is directly from the company itself. If at least one share is owned, most companies will allow the purchase of shares directly from the company through their investor relations departments. However, the initial share of stock in the company will have to be obtained through a regular stock broker. Another way to buy stock in companies is through Direct Public Offerings which are usually sold by the company itself. A direct public offering is an initial public offering in which the stock is purchased directly from the company, usually without the aid of brokers.

When it comes to financing a purchase of stocks there are two ways: purchasing stock with money that is currently in the buyer's ownership, or by buying stock on margin. Buying stock on margin means buying stock with money borrowed against the value of stocks in the same account. These stocks, or collateral, guarantee that the buyer can repay the loan; otherwise, the stockbroker has the right to sell the stock (collateral) to repay the borrowed money. He can sell if the share price drops below the margin requirement, at least 50% of the value of the stocks in the account. Buying on margin works the same way as borrowing money to buy a car or a house, using a car or house as collateral. Moreover, borrowing is not free; the broker usually charges 8–10% interest.

Selling

Selling stock is procedurally similar to buying stock. Generally, the investor wants to buy low and sell high, if not in that order (short selling); although a number of reasons may induce an investor to sell at a loss, e.g., to avoid further loss.

As with buying a stock, there is a transaction fee for the broker's efforts in arranging the transfer of stock from a seller to a buyer. This fee can be high or low depending on which type of brokerage, full service or discount, handles the transaction.

After the transaction has been made, the seller is then entitled to all of the money. An important part of selling is keeping track of the earnings. Importantly, on selling the stock, in jurisdictions that have them, capital gains taxes will have to be paid on the additional proceeds, if any, that are in excess of the cost basis.

Stock price fluctuations

The price of a stock fluctuates fundamentally due to the theory of supply and demand. Like all commodities in the market, the price of a stock is sensitive to demand. However, there are many factors that influence the demand for a particular stock. The fields of fundamental analysis and technical analysis attempt to understand market conditions that lead to price changes, or even predict future price levels. A recent study shows that customer satisfaction, as measured by the American Customer Satisfaction Index (ACSI), is significantly correlated to the market value of a stock. Stock price may be influenced by analyst's business forecast for the company and outlooks for the company's general market segment. Stocks can also fluctuate greatly due to pump and dump scams.

Share price determination

At any given moment, an equity's price is strictly a result of supply and demand. The supply, commonly referred to as the float, is the number of shares offered for sale at any one moment. The demand is the number of shares investors wish to buy at exactly that same time. The price of the stock moves in order to achieve and maintain equilibrium. The product of this instantaneous price and the float at any one time is the market capitalization of the entity offering the equity at that point in time.

When prospective buyers outnumber sellers, the price rises. Eventually, sellers attracted to the high selling price enter the market and/or buyers leave, achieving equilibrium between buyers and sellers. When sellers outnumber buyers, the price falls. Eventually buyers enter and/or sellers leave, again achieving equilibrium.

Thus, the value of a share of a company at any given moment is determined by all investors voting with their money. If more investors want a stock and are willing to pay more, the price will go up. If more investors are selling a stock and there aren't enough buyers, the price will go down.
Note: "For Nasdaq-listed stocks, the price quote includes information on the bid and ask prices for the stock."[18]

Of course, that does not explain how people decide the maximum price at which they are willing to buy or the minimum at which they are willing to sell. In professional investment circles the efficient market hypothesis (EMH) continues to be popular, although this theory is widely discredited in academic and professional circles. Briefly, EMH says that investing is overall (weighted by the standard deviation) rational; that the price of a stock at any given moment represents a rational evaluation of the known information that might bear on the future value of the company; and that share prices of equities are priced efficiently, which is to say that they represent accurately the expected value of the stock, as best it can be known at a given moment. In other words, prices are the result of discounting expected future cash flows.

The EMH model, if true, has at least two interesting consequences. First, because financial risk is presumed to require at least a small premium on expected value, the return on equity can be expected to be slightly greater than that available from non-equity investments: if not, the same rational calculations would lead equity investors to shift to these safer non-equity investments that could be expected to give the same or better return at lower risk. Second, because the price of a share at every given moment is an "efficient" reflection of expected value, then—relative to the curve of expected return—prices will tend to follow a random walk, determined by the emergence of information (randomly) over time. Professional equity investors therefore immerse themselves in the flow of fundamental information, seeking to gain an advantage over their competitors (mainly other professional investors) by more intelligently interpreting the emerging flow of information (news).

The EMH model does not seem to give a complete description of the process of equity price determination. For example, stock markets are more volatile than EMH would imply. In recent years it has come to be accepted that the share markets are not perfectly efficient, perhaps especially in emerging markets or other markets that are not dominated by well-informed professional investors.

Another theory of share price determination comes from the field of Behavioral Finance. According to Behavioral Finance, humans often make irrational decisions—particularly, related to the buying and selling of securities—based upon fears and misperceptions of outcomes. The irrational trading of securities can often create securities prices which vary from rational, fundamental price valuations. For instance, during the technology bubble of the late 1990s (which was followed by the dot-com bust of 2000–2002), technology companies were often bid beyond any rational fundamental value because of what is commonly known as the "greater fool theory". The "greater fool theory" holds that, because the predominant method of realizing returns in equity is from the sale to another investor, one should select securities that they believe that someone else will value at a higher level at some point in the future, without regard to the basis for that other party's willingness to pay a higher price. Thus, even a rational investor may bank on others' irrationality.

Arbitrage trading

When companies raise capital by offering stock on more than one exchange, the potential exists for discrepancies in the valuation of shares on different exchanges. A keen investor with access to information about such discrepancies may invest in expectation of their eventual convergence, known as arbitrage trading. Electronic trading has resulted in extensive price transparency (efficient-market hypothesis) and these discrepancies, if they exist, are short-lived and quickly equilibrated.

The capital stock (or simply stock) of a business entity represents the original capital paid into or invested in the business by its founders. It serves as a security for the creditors of a business since it cannot be withdrawn to the detriment of the creditors. Stock is different from the property and the assets of a business which may fluctuate in quantity and value.