2. Mechanics: What the Price of an Option Is Made Of

2. Mechanics: What the Price of an Option Is Made Of

Monday, and the market closed right where it opened: the index didn't move half a percent all day. Yet the call you had been watching since morning is down seven. The asset stands still — the option bleeds money. Where is it draining to?

The answer is hidden in the anatomy of the premium. In the last lesson we paid one price for the right and never asked where it came from. Now we ask: it is out of the makeup of the price that the greeks grow, and volatility, and everything our indicators will measure.

The two parts of the premium

Take a call at the 100 strike with the asset at 104. The right to buy at 100 something worth 104 has an obvious value: four points you could pocket right now. Those four points are called intrinsic value — what the right is worth if exercised immediately.

But on the market this call trades not at four points but at, say, six and a half. Where do the other two and a half come from? That is time value — the price of what might still happen before expiration. The asset has time to rise further, and the market charges money for that chance.

The chart shows both parts at once. The white dashed line is intrinsic value: zero to the left of the strike, a straight line to the right — the familiar kink of the payoff diagram from lesson 1. The green curve is the market premium a month before expiration. The yellow layer between them is that very time value. Notice where it is thickest: right at the strike. That is where uncertainty peaks — the option's fate could be decided either way.

By where the price sits relative to the strike, options fall into three classes, and these words will be everywhere: in the money (ITM) — intrinsic value already exists; at the money (ATM) — the price sits right at the strike; out of the money (OTM) — no intrinsic value, the entire premium is time value. Cheap OTM options are those "lottery tickets" from lesson 1: a right that has yet to acquire a meaning.

Now Monday's riddle solves itself. The call from the start of this lesson had no intrinsic value — only time value. A day passed, nothing happened, the chances of "making it in time" shrank — and the time value withered. Nobody stole the money: it drained away to the same place a year's prepaid insurance drains to — into the past, one day at a time.

Volatility: the price of uncertainty

Time value depends on time to expiration — that much is intuitive. The second factor is less obvious and far more important for everything ahead: it depends on how wide the market sees the fan of future outcomes.

Both curves on the chart are the market's picture of where the asset will end up by expiration. The blue one is a calm market: nearly all scenarios crowd around the current price, the tail beyond the 105 strike is skinny, and the call at that strike trades for pennies. The red one is a nervous market: the bell has spread out, the distant scenarios have become genuinely possible, and that very same strike has gone from "unlikely" to "easily." The contract itself hasn't changed — same strike, same expiration. Only the market's expectations have changed, and the option's price is now several times higher.

The width of that bell is volatility. And now the main trick. Nobody tells the market the correct width — nobody knows it. The logic runs in reverse: we see what options are actually trading for, and we compute what bell width those prices imply. Hence the name — implied volatility (IV). IV is not an analyst's forecast. It is the consensus of everyone putting real money on the line about the size of the uncertainty ahead.

One subtlety people trip over constantly: the bell widens in both directions at once. IV measures the reach of expectations, not their direction — ahead of a major news release it rises whatever the market's mood, because the market knows a move is coming but not which way.

That is exactly why option prices are a unique source of information: baked into them is the collective expectation of a move's magnitude. The famous VIX — the "fear index" from the news — is computed precisely this way: out of the prices of S&P 500 options, the implied width of the bell one month ahead is extracted.

The chain: hundreds of instruments on a single asset

A stock has one price. Options on that same stock come as an entire table: it is called the option chain (or the board). Rows are strikes, spaced five points apart on the indexes; each strike gets a call and a put; and the whole table repeats for every expiration date. Multiply it out: dozens of strikes by dozens of dates by two types — one underlying carries thousands of separate instruments, each with its own price, its own volume, and its own life.

In every cell of the chain, besides the quotes, live two numbers that matter to us critically. Telling them apart is a required skill for this entire course.

Volume — how many contracts traded today. The counter resets every morning. It is a measure of activity: where the fight was today.

Open interest (OI) — how many contracts exist right now: opened and not yet closed. It is a measure of accumulated positions: where the money is standing.

The mechanics linking them are subtler than they look. A trade changes OI only when both sides open new positions: buyer A and seller B created a contract — OI rose by one. If instead A buys to close his old short while B sells to close his old long, the contract is extinguished — OI fell. And if one side opens while the other closes, the contract simply changed hands — OI didn't budge. Volume, meanwhile, rises in all three cases. A hundred thousand contracts of volume can mean anything: fresh money flowing in, old money fleeing, or plain pass-the-parcel. And even a rise in OI says nothing by itself about who arrived: every contract has two sides, and every new long is matched by a new short. Who exactly stood behind the trade is precisely what the classic data does not contain at all. Remember this ambiguity: half of the conversation about data will rest on it.

Expirations: the calendar the market lives by

The classic rhythm of the options market is monthly: the main series expire on the third Friday of the month. The market calls that day OPEX (option expiration) — a word you will meet again both in this course and in our indicators. The monthly series are the oldest and the heaviest: institutional hedges and structured products live in them for months and accumulate the largest stockpiles of positions, so their expiration brings the biggest mechanical reshuffles of the month. Then the exchanges added weekly series, and on the S&P 500 index options now expire every trading day — how that changed the market deserves a lesson of its own, and that is where our main story begins.

On SPX the two families of series differ even by ticker, and the difference will matter to us later:

SPX — the monthly series. They settle in the morning: the final price is set by the market's open on the third Friday, and formally the series expires at 09:15 New York time — earlier than the regular session even opens. So on that Friday itself the monthly series no longer trades: its fate was decided at the open.

SPXW — the weekly (and daily) series. They settle in the evening, at 16:00 with the market close; on shortened pre-holiday days, at 13:00.

This produces a detail that confuses even professionals: on the date of the third Friday there live two series with the same expiration date — the morning monthly SPX and the evening weekly SPXW. The morning one dies at 09:15; the evening one trades all day. Whoever says "the Friday expiration" must specify which — and our indicators, as we will see, keep them strictly apart, down to the exact expiry time.

Two technical distinctions to finish — boring right up until the moment the picture stops adding up without them.

Exercise style. An American option can be exercised on any day up to expiration; a European option — only on the expiration date. The names reflect no geography: both trade in Chicago. SPX options are European.

Settlement form. Stock options end in delivery when exercised: the call buyer receives the actual shares. An index cannot be delivered — nobody is going to cart around a sack of five hundred stocks in the right proportions — so index options are settled in cash: the losing side simply pays the difference.

The SPX complex: one ecosystem

Let's now assemble the family of instruments this entire course is built around.

SPX — the S&P 500 index itself. It is a number, not a commodity: you cannot buy "one SPX." But options exist on that number — European-style, cash-settled, with a multiplier of one hundred dollars per point. It is the largest equity options market in the world, and it trades on the CBOE.

ES — the S&P 500 futures on the CME. This is what our users trade, and this is the chart our indicators live on.

SPY — the exchange-traded fund tracking the index; the retail version of the same thing, ten times smaller in notional.

VIX — not an instrument but a thermometer: implied volatility extracted from the prices of SPX options.

The family's key property: all its members are locked together by arbitrage. Let the ES price drift away from the SPX level — and arbitrageurs will eat the difference within seconds. That is why events on one market of the family echo instantly across the rest — and the hedging trades of SPX option dealers land straight in the ES futures, in the very order book our traders watch. Later in the course we will hop freely between "the index," "SPX," and "ES" — now you know why that is legitimate.

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The premium, as we now see, depends on three things at once: where the price sits relative to the strike, how much time remains, and how wide the bell of expectations is. Change any one — and the premium changes. Professionals long ago stopped discussing an option's price as a single number: they took its sensitivity apart into components and gave each one the name of a Greek letter. That language — delta, gamma, theta, vega — is the next lesson. It is also the last step before meeting the main character of the course.