The term "equity" in corporate or project finance jargon indicates some share of ownership in a company or project - i.e., some level of entitlement to some slice of the revenues brought in by the company or project. There are different priority levels of this entitlement - typically operating costs must be paid (including, in some cases borrowing costs) before equity investors can get their slice of the net revenues. There are also multiple priority levels of equity investors, which determines who gets paid first if profits are scarce.
The simplest, and one of the most common, forms of equity ownership is through the ownership of company stock. A share of stock is simply an ownership right to a portion of the company's profits. When public stock is initially issued by a company (called an "initial public offering"), the price paid for that stock is effectively a capital infusion for the company.
When you think about shares of stock, you may have in your mind things that are traded on the New York Stock Exchange. Not all stock is traded or issued this way, at least not initially. Often, company founders or owners will decide to sell limited amounts of stock in a company without that stock being available for the general public to purchase or being traded on an exchange like the New York Stock Exchange. A company that issues stock in this way is often referred to as being a "private" company, which means that its stock is held and traded (if it's ever traded) in the hands of individuals or institutions selected by the company. Often times, stock in a private company comes with some sort of voting right or other representation into how the company runs its operations.
A company that issues shares of stock to the general public is called a "publicly-traded" or "public" (for short) company. The term "public" in this case should not be confused with ownership by any government or the mission of the company - the term simply refers to the availability of the company's stock. The decision to "go public" is complicated and has costs as well as benefits. The obvious benefit is that issuing public stock is a relatively straightforward way to raise large amounts of capital. Owners of private stock that allow their stock to be sold in the public offering can also make substantial amounts of money if the demand for the stock among the public is high. There are, however, a couple of big down sides. First, issuing more shares of stock effectively dilutes the value of existing shares. If a company has $1 million in profits over a time period and increases the number of shares of stock from 1 million to 2 million, then the earnings per share of the company drops from $1 per share to $0.50 per share over that time period. People are sometimes willing to pay large sums for company stock if they believe that profits will increase in the future. Second, the more equity investors there are (public or private), the larger the loss of control by the company's initial shareholders.
Raising equity capital can happen through a number of different channels. Brief descriptions of a few of the major channels follow:
The "cost of equity" for a project or company represents the return that an equity investor would need in order to judge that project or company a worthwhile investment. Remember that the cost of equity is really an opportunity cost. Individual investors may have their own criteria for judging opportunity cost, and we can't get into their heads all of the time. So, how do we estimate opportunity cost for a particular project or company? The most common framework is to use a framework called the "Capital Asset Pricing Model" (CAPM). Investopedia has a nice introduction to this framework [2] that includes both the intuition and the equations. Here, we will stick mostly to the intuition.
Using the CAPM to determine the cost of equity, the equation is:
For project evaluation, it is common to use the beta and risk premium relevant to the industry in which the project is going to operate (e.g., utilities for a power plant or gasoline for a refinery). This web page has a nice table estimating the cost of equity for different industries [3].