Accounting
- Assets are what you have. The tangible and intangible things that you control that are worth money.
- Liabilities are what you owe. The debts that you are obliged to repay to other people at some point in the future.
- Equity is what you own. That is, how much of the assets you get to keep after you repay every one of your liabilities.
Equity is the accounting or book value of the company. It is not a particularly useful measure as all of this is theoretical point-in-time stuff. It’s not possible in most cases to immediately settle your debts and assets and liabilities will change, possibly second-by-second as the organisation does whatever business it does.
More useful measures are its value as a going concern which is the present day value of all the expected future cash flows the company will deliver to its owned; this is typically more than its book value. And it’s liquidation value which is what the owners would be left with if it stopped trading, sold all the assets for whatever it could get, and paid all the liabilities (including the ones that crystallised because of all the contracts you just broke); this is typically less than the book value. However, if the liquidation value is ever higher than the going concern value, it’s time to appoint a liquidator.
When a company creates and sells stocks on the primary market, it books both cash (an asset) and shareholder’s equity (an equity). There are no liabilities involved here from an accounting point of view.
Financial markets
An equity is a class of assets representing an ownership stake in a company. Other classes of assets include cash representing money in the bank, bonds representing a loan to a company or government, property representing an ownership stake in real estate, commodities representing an ownership stake in physical stuff like wheat or gold, and currencies representing ownership of foreign cash.
The trading of stocks on the secondary market does not affect the accounts of the company. Public companies are usually listed on a stock exchange which allows the free trading of shares in the company between anyone, however, there are some unlisted public companies. Owners of private companies must trade their shares privately and other owners can typically veto trades.
The value of a share on the secondary market its value as part of a going concern. Most relevantly, for the stockholder, the value of owning the share is the net present value (to them) of all the cash flows that that share will generate. This includes semi-annual dividends for as long as they hold the share (noting that some companies don’t pay dividends) plus the cash they will get when they ultimately sell it. Additionally, there are intangible benefits such as being able to attend and (possibly) vote at company meetings, and, if you own enough of the shares, the right to decide directly who one or more directors of the company will be (i.e. real control).
The share’s value to someone else is almost surely going to be different (higher or lower) than its value to you. And wildly different from the amount the company originally sold it for on the primary market, possibly many years ago. If someone is willing to pay you more for something you own than you think it’s worth, you should probably sell it to them.
However, that’s too simplistic for the way real people behave. There are always other reasons to sell (or buy) beyond an assessment of the net present value of future cash flows. For example:
- Perhaps you have an opportunity to buy a nice car or beach house. To get that thing you want you need cash which may mean you are willing to sell shares for less than you think they’re worth.
- Perhaps you’re dead and your executor wants to liquidate all your assets to distribute cash to the beneficiaries.
- Perhaps you’re making a bid for control of the company - the value of that one share that will give you control is obviously more than the 9,999 that won’t.
- Perhaps you have had an ethical epiphany and no longer want to own shares in companies that make weapons/alcohol/meat/fossil fuel/etc. or companies that finance those that do.
- Perhaps you had a tarot reading and the psychic told you there was going to be a stock market crash.
- Perhaps you own all the shares in your company and want to retire.
Just looking at the stock market, what it does is in its name: it’s a market for stocks. Just like a supermarket is a market for … groceries. It’s purpose is to bring together people who want to buy and people who want to sell, allow them to state the price their willing to pay or take respectively, and, if these overlap, make the deal happen. These days it’s all done automatically by computerisation but I’m just old enough to remember stock brokers on the floor shouting out those prices and finding each other over the din.
Law
While it’s not something I think you’re interested, equity is that part of law concerned with things that were dealt with by the now defunct Courts of Chancellery as distance from those dealt with by the Law Courts. It includes things like wills, trusts, and equitable remedies such as specific performance, injunctions, and unjust enrichment.
Generally
Equity is sometimes used as a synonym for fairness in a sociological context.