Unit 1 of 15 · Beginner

What happens at the end

In one read

Exercise is the option buyer invoking their right — a call buyer buying at the strike, a put buyer selling at it. Assignment is the mirror on the writer's side: when a buyer exercises, the clearing house assigns a writer who must deliver. Settlement is how the delivery happens. Physically-settled options hand over the actual shares at the strike; cash-settled options (common on index contracts) just pay the in-the-money difference in cash. Most in-the-money options are handled automatically at expiry, and out-of-the-money ones simply expire worthless. Pin risk is the edge case: when price finishes almost exactly at the strike, whether an option lands in- or out-of-the-money — and so whether it is assigned — can flip on the last prints. This unit walks one generic contract through expiry so the ending stops being a mystery.

Exercise, assignment, settlement — the three words for the ending

Most option positions never get here at all — they are closed with an offsetting trade before expiry. For a contract actually held to the end, the life ends in one of two ways: it is exercised, or it expires. Three terms describe the mechanics:

  • Exercise — the buyer invoking their right. A call buyer buys the underlying at the strike; a put buyer sells at the strike.
  • Assignment — the matching event on the writer's side. When a buyer exercises, the clearing house (the OCC, for listed US options) assigns a writer, who must fulfil the obligation: deliver the shares (or the cash).
  • Settlement — how delivery happens. Physical settlement moves the actual shares at the strike. Cash settlement — typical for index options — skips the shares and just pays the in-the-money difference.

Most ITM options are exercised automatically at expiry; OTM options expire worthless and nothing changes hands.

A worked example

A GENCO $100 call is held to expiry.

  • GENCO settles at $107. The call is $7 ITM. Under physical settlement the buyer exercises, buys 100 shares at $100, and a writer is assigned to sell them. Under cash settlement, the buyer simply receives $7 × 100 = $700 and no shares move.
  • GENCO settles at $96. The call is OTM; it expires worthless. No exercise, no assignment, nothing to settle.

Now the awkward case. GENCO settles at $100.02 — a hair ITM. Pin risk is exactly this: at a settle sitting right on the strike, whether the contract finishes in- or out-of-the-money can flip on the final prints, and with it whether anyone is assigned. Positions that looked closed can turn out open, or the reverse — which is why expiration at the strike is the one moment that demands attention rather than assumption.

See it in kestrel

Expiry is a moment on a real session, not an abstraction. Run one and watch where price actually settles:

npx kestrel.markets sim fomc-rate-decision-whipsaw

That runs a deterministic simulation over a generic index session — managed licensed data, no wall time, no signup, no card — and prints a certified proof URL. Because the settle is recorded on the tape, whether a contract finishes ITM or OTM is a fact you can check, not a story. Recompute the whole record on your own machine, byte for byte:

npx kestrel.markets certify https://kestrel.markets/proof/art_d29415f0cf502f4a218a9cba

Keep the ending one command away: drop the kestrel.markets MCP server into your client and the next session opens where this one left off — no account in between.

Recompute it

Every claim in this unit recomputes from a certified proof — no account, no card.

/proof/art_d29415f0cf502f4a218a9cba
Keep readingMoneyness and the clock

Agent twin: /education/options/opt-exercise-assignment-settlement/content.md