U.S. Option Symbology
For educational purposes only; not investment advice.
Direct answer
Section titled “Direct answer”The standard OSI option key identifies a U.S. listed option series with 21 characters: a six-character root, a six-digit expiration date, one call/put character, and an eight-digit strike field. Reading it reduces order-entry mistakes, but the key alone does not establish the multiplier, deliverable, exercise style, settlement method, or last trading time.
How the fields work
Section titled “How the fields work”The fixed-width layout is:
ROOT__ + YYMMDD + C/P + STRIKE×1000
The root occupies six positions and is right-padded with spaces. The date uses year, month, and day. C means call and P means put. The strike is stored as an integer with three implied decimal places, padded to eight digits; divide it by 1,000 to recover the displayed strike.
Spaces matter in machine data even when a screen removes them. A broker may show a compact symbol, a friendly series label, or its own identifier. Treat those as display mappings and verify the readable underlying, exact expiration, side, and strike on the order ticket and confirmation.
Worked example
Section titled “Worked example”Consider the hypothetical key AAPL 270115C00150000:
| Positions | Value | Meaning |
|---|---|---|
| 1–6 | AAPL·· |
root AAPL, followed by two spaces |
| 7–12 | 270115 |
expiration date January 15, 2027 |
| 13 | C |
call |
| 14–21 | 00150000 |
150000 ÷ 1,000 = $150.000 strike |
Thus the key describes an AAPL January 15, 2027 $150 call series. It does not prove that one contract delivers 100 ordinary shares. Before trading, inspect the contract specification and any OCC information memo. A corporate action can create an adjusted option with a different root or deliverable even when its strike and expiry look familiar.
Verification and risks
Section titled “Verification and risks”- Compare the full key, not only the root or strike; weekly and standard monthly series can differ only by date.
- Preserve leading zeros in the strike field and spaces in the root when processing data.
- Do not infer the economic underlying solely from an unfamiliar adjusted root.
- Confirm multiplier, pricing unit, complete deliverable, exercise style, settlement, expiration procedures, and broker cutoff separately.
- Market-data vendors can use different display aliases; mapping errors can join quotes or positions to the wrong series.
Common misconceptions
Section titled “Common misconceptions”“The last eight digits are dollars.” They are thousandths of a dollar; 00150000 represents $150.000, not $150,000.
“Every symbol represents 100 shares.” Standard equity options commonly use 100 shares, but adjusted contracts can have different deliverables.
“The symbol contains every contract term.” It identifies a series; authoritative specifications and OCC notices supply terms the key omits.