Exercise flows through the OCC, the clearinghouse behind every listed option: holders exercise against the OCC, which assigns a member firm at random, and your broker allocates impartially among its short customers. Assignment is a lottery, not a grudge. A short put assigned means strike × 100 in cash leaves and 100 shares arrive overnight; anything about a penny in the money at expiry is auto-exercised.
Early assignment is rare while your short option keeps real extrinsic value, because exercising forfeits it — a rational holder sells instead. The shield drops in two cases: deep in-the-money options trading at pure intrinsic, and short ITM calls the night before an ex-dividend date when the dividend exceeds the remaining time value. Check extrinsic and the ex-date and you know exactly which nights you're in the raffle.
The wheel's accounting collapses to one running number: adjusted cost basis = assignment price minus every premium collected, puts and calls alike — with roll debits raising it. Assigned at $95 after $2 of put premium, your basis is $93 on day one; two $2 covered calls later it's $89. Judge the campaign, not the leg: a call-away at $95 against a $91 basis is a +$400 campaign regardless of what the final call did.
The interactive cycle diagram walks the full loop — cash, cash-secured put, assignment, shares, covered call, called away — with a spin-the-wheel button and a live ledger showing basis grinding lower each turn. Then run it for real in the Wheel Tracker, which keeps one honest adjusted basis per campaign.
Educational, not investment advice.