# 0DTE

**OPT-12 · Core Options · Core**

**Lesson question:** What changes when little time remains?

Original fictional examples; educational writing, not live market data, orders or production approval.

## By the end

- Explain the mechanism in the lesson question.
- Reproduce the worked comparison and recognize its failure case.

**Prerequisites:** OPT-F01, OPT-F02, OPT-F03, OPT-F04

Zero-days-to-expiry describes remaining contract life, not a different set of profit rules. Near strike, Delta and Gamma can change rapidly while there is little time for a failed entry to recover.

A cheap premium or defined terminal spread does not make the trade operationally trivial.

## Understand the mechanism

Long options can lose all premium. Short options and spreads add exercise, assignment, settlement and potentially discontinuous liquidity concerns. Product rules differ: some index options are cash settled while equity options can create shares.

An option far from the strike may have very different sensitivity from one at the money. Exact expiry is a boundary, not a tiny positive-time approximation.

## Walk through the process

Use the actual product schedule and settlement method. Define exposure, feasible exits and what happens if the position remains open. Model a fast move against the structure, not only the intended target.

Do not use 0DTE as a beginner default because its premium appears inexpensive.

## Contract and decision boundary

Terminal examples use simultaneous intrinsic realization of all stated legs, before unspecified costs. Actual American exercise, assignment, early liquidation and broker handling can create different interim cash needs. These fictional comparisons are education, not orders or personalized investment advice.

## A worked example

Hold a hypothetical ATM European option at S=K=100, sigma 25% and zero rate/yield. The graph compares Gamma at six, twelve, twenty-four and seventy-two hours expressed as fractions of a calendar year.

Its increasing near-strike concentration explains why a hedge ratio can shift quickly. This controlled model comparison is not a prediction of realized movement or a live same-day quote.

## Graph: 0DTE—worked comparison

**Horizontal:** Hours remaining (calendar convention)  
**Vertical:** ATM Gamma per USD

Fictional data from the written example. The chart organizes the comparison; its shape is not a forecast.

Complete numerical data are embedded in `scripts/options-strategies/OPT-12.js` and displayed as an accessible table in the HTML lesson.

## What would invalidate the reading?

Treating the final cents of premium as easy income can leave large late Gamma or assignment exposure. A planned exit may not occur before the relevant cutoff.

## Check your understanding

### Does low remaining premium mean low risk in every same-day structure?

**Answer:** No.

**Why:** Contract obligations, sizing and nonlinear exposure remain.

### What is the critical failure to avoid?

**Answer:** Treating the final cents of premium as easy income can leave large late Gamma or assignment exposure. A planned exit may not occur before the relevant cutoff.

**Why:** Explain this risk before treating the example as a decision rule. A correct calculation does not guarantee a favorable market outcome. **Critical risk check.**

## Takeaway

Return to the question: What changes when little time remains? State the observed facts, the assumptions and the failure condition separately.

## References and provenance

The cited references support definitions and conventions. The teaching prose, tickets and numerical scenarios are original; they are not attributed as historical market observations.

- [OCC Options Disclosure Document](https://www.theocc.com/company-information/documents-and-archives/options-disclosure-document)

- [OIC Strategy Reference](https://www.optionseducation.org/strategies/all-strategies-en)