Intro to Options

Options are the centerpiece of this unit and among the most versatile instruments in finance. The single feature that sets them apart from the forwards and futures you just met: an option grants a right without imposing an obligation. That one asymmetry opens up a wide range of strategies and payoff shapes, and understanding it is the key to everything that follows.

The defining asymmetry

An option is a contract that gives its holder the right, but not the obligation, to buy or sell an underlying asset at a set price within a set period of time. This is the key break from a forward or future, where both parties are obligated to transact. The option holder can exercise the right if it is advantageous, or simply let it expire if it is not. That freedom to walk away from a bad outcome while still capturing a good one is what gives options their distinctive asymmetric payoffs.

Two types, two sides

There are two basic types of option, which the next lesson details: a call grants the right to buy, and a put grants the right to sell. Every option also has two sides. The buyer, or holder, pays the premium to acquire the right. The seller, or writer, receives the premium and takes on the corresponding obligation: if the buyer exercises, the writer must fulfill the contract. The buyer holds the right, and the writer bears the obligation in exchange for the premium.

An option is the right to change your mind. You keep the good outcomes and walk away from the bad ones, and the premium is what that privilege costs.

The asymmetry of risk

The right-without-obligation structure creates a clear asymmetry between the two sides. The buyer's maximum loss is limited to the premium paid, since the worst case is letting a worthless option expire, while the potential gain can be large. The seller faces the reverse: the maximum gain is the premium received, while the potential loss can be substantial, even unlimited in some cases, because the seller must fulfill the contract no matter how far the price moves against them. This asymmetry between limited-risk buyers and large-risk sellers runs through the entire study of options.

Exercise styles and contract size

Two practical details matter from the start. Options come in different exercise styles: an American-style option can be exercised any time before expiration, while a European-style option can be exercised only at expiration. And in US equity markets, one standard option contract typically covers 100 shares of the underlying stock, so premiums and payoffs scale by 100. A premium quoted as 2 dollars therefore costs 200 dollars for one contract.

You now have the vocabulary of options and their core asymmetry. The next lesson makes it concrete by examining the two building blocks in detail, calls and puts, and drawing their payoffs.