The Options Contract: What You Are Actually Agreeing To

Every options trade is a contract between two parties. The buyer gets a right. The seller takes on an obligation. Money changes hands the moment the trade is placed, and the rest of the contract plays out over the days or weeks that follow.

Most beginner explanations of options skip straight to strategy. Strategy is the fun part, and it's where the money is made or lost. But strategy only makes sense once you understand the contract underneath it. This piece walks through the mechanics. No tricks, no jargon for its own sake. Just what each party has agreed to, who else is involved, and what happens when the clock runs out.

The 100-Share Multiplier

The first thing to know about a standard equity options contract is that it does not represent one share of stock. It represents 100 shares.

This matters because option prices are always quoted per share. If you see a call option quoted at $2.00, the actual cost to buy one contract is $200. If you sell a covered call and collect $1.50 in premium, you are collecting $150 in cash, not $1.50.

A $5.00 move in the option price is a $500 move per contract. Every dollar of premium is a hundred dollars of cash. This arithmetic is the foundation of everything else, and getting comfortable with it before placing a first trade is not optional.

One small wrinkle worth knowing: stock splits, special dividends, and mergers can change a contract's deliverable, so the 100-share figure assumes the underlying has not had a corporate action that adjusted the contract. For standard, unadjusted contracts on widely traded names, the 100-share number holds.

What the Buyer Agreed To

The buyer pays the premium at the moment the trade is placed. In exchange, the buyer receives one thing: the right to buy shares at the strike price (if the contract is a call) or sell shares at the strike price (if the contract is a put) at any point on or before expiration.

That right is all the buyer gets. The premium paid is all the buyer owes. After entry, the buyer can use the right, sell the contract to someone else for whatever it is worth, or walk away and let it expire. The premium is the maximum loss. Nothing more can be required of the buyer.

What the Seller Agreed To

The seller collects the premium at the moment the trade is placed. In exchange, the seller takes on an obligation. If a buyer of that contract decides to exercise, someone on the short side must perform.

For a call seller, performing means delivering 100 shares of the underlying at the strike price. For a put seller, performing means buying 100 shares of the underlying at the strike price.

The premium is keep-no-matter-what money. The obligation, though, is real, and it triggers based on what the buyer decides to do. This is why the seller's side of the options market asks for more attention to position sizing, more awareness of risk, and more discipline around management rules. The obligation to perform is binding once it lands.

The Quiet Third Party: The OCC

There is a third party in every options contract, and it deserves a mention even though it stays in the background. The Options Clearing Corporation, usually just called the OCC, is the central counterparty to every listed options trade in the United States.

When you buy a call, you are not really contracting with the specific seller on the other side of the screen. You are contracting with the OCC, which has stepped in between buyer and seller and guaranteed performance on both sides. The same is true when you sell. The seller's obligation runs to the OCC, not to a specific buyer.

This is what makes options tradable. Because the OCC stands in the middle, you can sell your long contract to a new buyer at any time without finding the original seller. You can buy back a short contract without locating the original holder. The OCC handles the bookkeeping and guarantees the contract no matter who happens to be on the other side at any given moment.

It also means assignment is random. When a buyer exercises a contract, the OCC selects an account on the short side at random from the pool of every open short position in that series. Your broker then assigns one of its customers, again typically at random. The specific person you sold to is not the person who triggers your assignment. There is no personal relationship in this market. Just contracts and a clearing house in the middle.

Exercise, Assignment, and Expiration

Three mechanics govern the life of every options contract: exercise, assignment, and expiration.

Exercise is the act of a buyer using the right embedded in the contract. Assignment is what happens on the short side when someone exercises. Expiration is the day the contract must resolve, one way or the other.

Most US equity options are American-style, meaning they can be exercised at any time before expiration. European-style options can only be exercised at expiration itself.

One practical wrinkle is worth flagging. Index ETFs and the index products that track the same names often have different exercise styles. SPY options, for example, are American-style and settle in shares because SPY is an ETF. SPX options, on the same broad index, are European-style and settle in cash. QQQ versus NDX, IWM versus RUT, same pattern. A beginner who assumes "index option" always means European can get a real surprise the first time they trade SPY.

In practice, most options are closed before expiration rather than exercised. The market for buying and selling contracts is liquid enough that taking profits or cutting losses by closing the trade is almost always more efficient than exercising. But the right to exercise is what gives the contract its value, so the mechanics matter even when they do not come into play.

For covered call and cash-secured put sellers, assignment is not a disaster. It is the planned outcome that was priced in at entry. A covered call seller whose shares are called away sells them at the strike they agreed to. A cash-secured put seller who is assigned buys shares at the strike they were willing to pay. Both outcomes were chosen ahead of time.

What Happens at Expiration

At expiration, every options contract resolves in one of two ways.

If the contract is in the money by at least $0.01 at expiration, the OCC exercises it automatically under a rule known as exercise by exception. The long side becomes long shares (for calls) or short shares (for puts), and someone on the short side gets assigned. The buyer can override auto-exercise by submitting a "do not exercise" instruction to their broker before expiration, but absent that instruction, an in-the-money option will be exercised by the system on the buyer's behalf.

If the contract is out of the money at expiration, it expires worthless. The buyer loses the premium. The seller keeps the premium. The obligation is gone.

A practical note on the buyer side: many brokers will close out a long, in-the-money option on expiration day if the customer does not have the buying power or the shares to handle assignment. This is a broker risk policy, separate from the OCC's auto-exercise rule. Beginners holding long options into expiration should know their own broker's policy. Cash-settled index options like SPX skip this altogether and simply settle in cash.

There is no middle ground at expiration. No negotiation. No partial exercise within a single contract. The strike either had value at the close or it did not, and the contract settles accordingly. One small clarification, since this trips people up: if you hold multiple contracts in the same series, you can choose to exercise some and let others expire. The all-or-nothing rule applies within a single contract, not across a position.

Sellers Are Not Powerless

One thing worth saying directly. Sellers are not stuck waiting for assignment to happen. A short option can be closed at any time the market is open by buying the same contract back. Most assignment surprises happen because the seller did not close a position they probably should have closed, not because assignment came out of nowhere.

Defined management rules, such as closing at a profit target or rolling before expiration week, are the seller's real defense. Assignment is what happens when none of those rules fired.

Frequently Asked Questions

What does it mean to exercise an options contract?

Exercising means using the right the contract gives you. The buyer of a call exercises by buying 100 shares at the strike. The buyer of a put exercises by selling 100 shares at the strike. Exercise triggers assignment on the short side, and someone holding a short contract in the same series gets the obligation. In practice, very few options are exercised before expiration. Most are closed or expire.

What happens if I sell a covered call and the stock rises above my strike price?

If the stock is above your strike at expiration, your shares will most likely be called away at the strike price. You sell the shares at the strike you agreed to, and you keep the premium you collected. After assignment, you no longer own the shares. This is a planned outcome, not a failure. The work happens at entry: choose a strike you would be content to sell at, on a stock you understand.

Can I be assigned before expiration?

Yes, on American-style options, which covers most US equity options. Early assignment is possible any time the contract is in the money, but it is unusual. The most common case is a call that is deep in the money and has little extrinsic value left, particularly around an ex-dividend date, when a call holder may exercise to capture the upcoming dividend. A useful rule of thumb: when the remaining extrinsic value in a call is less than the upcoming dividend, early assignment becomes a real risk. Outside that scenario, early assignment is rare but always possible. Plan for it as part of running short positions.

Is the broker my counterparty?

Not exactly. The OCC is the counterparty on every listed US options contract. The broker is the connection between you and the OCC, and it handles the customer-side mechanics like collecting margin, processing exercise requests, and assigning customers when assignment notices come in. The contract itself is between you and the OCC.

A Closing Thought

Reading this far is not glamorous work. The contract mechanics are not where money is made. But they are where money is lost when a trader does not know what they actually agreed to.

Every strategy I write about sits on top of the framework above. Covered calls, cash-secured puts, credit spreads, iron condors, the wheel, poor man's covered calls, all of it. Understanding the contract well costs nothing. Misunderstanding it can cost a lot.

Andy

Next in this series: How to Read an Options Chain Without Getting Overwhelmed takes the contract mechanics covered here and shows you where to find every piece of this information in a real options chain before you place a trade. And In the Money, At the Money, Out of the Money: Once and for All covers the moneyness categories that directly affect which contracts get exercised at expiration.

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This newsletter is for educational purposes only and should not be considered investment advice. Options trading involves significant risk and is not suitable for all investors. Past performance does not guarantee future results. Always consult with a qualified financial professional before making investment decisions.