Buyer versus seller

Every option contract has two sides. For every buyer who holds the right, there is a seller who granted it, and their positions are mirror opposites. Understanding both sides, even if you only ever plan to buy, is what keeps you from misjudging the risk on either one.

The buyer: pays, and holds the right

The buyer of an option pays the premium and, in return, holds the right without any obligation. A buyer can lose no more than the premium, whatever happens to the underlying, and stands to gain a large amount if the underlying moves the right way. The buyer alone decides whether to use the option or let it lapse. In short: limited risk, large potential reward, and full control over whether to act, paid for with the premium and with the steady pressure of time.

The seller: is paid, and takes the obligation

The seller, also called the writer, is the mirror image. The seller receives the premium up front and, in exchange, takes on the obligation to honour the contract if the buyer chooses to exercise. If the option expires worthless, which happens often, the seller simply keeps the premium as profit. But if the underlying moves against the seller, the loss can be large, and for a call seller it can be very large, because there is no ceiling on how high a price can climb. In short: limited reward (the premium), potentially large risk, no control over whether the buyer exercises, in return for being paid up front and having time on their side.

The asymmetry at the heart of options

Set the two side by side and the shape of options appears. The buyer has limited risk and large potential reward, but pays the premium and fights the clock. The seller has limited reward and large potential risk, but is paid the premium and is helped by the clock, since an option losing its time value is exactly what lets a seller keep it. This is not a fair-sounding symmetry, and it is not meant to be. Each side is paying for, or being paid for, a different thing. It is the single most important idea to carry through the rest of the course.

One more point clears up a lot. Before costs, an option is a transfer between the two sides: what the buyer gains, the seller loses, and the other way around. The premium is simply the price the two agreed on for that arrangement.

What to carry forward

An option is a two-sided contract. The buyer pays the premium, holds the right with no obligation, risks only the premium, and is worn down by time. The seller collects the premium, carries the obligation, can lose much more than they made, and is helped by time. That asymmetry, limited risk while fighting the clock on one side, paid but exposed on the other, sits under every options decision you will make, and it is why selling is never the easy income it is sometimes made out to be.

That completes the foundation. You know what an option is, why it exists, the two types, the three numbers, and the two sides. The next part begins to read an option's value, starting with the two ingredients hidden inside every premium: intrinsic value and time value.