# Day trading options

**OPT-10 · Core Options · Core**

**Lesson question:** Why can correct direction still produce a losing trade?

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

An intraday option trade combines the underlying's move with changing sensitivity, IV, time and execution costs. The option is not a fixed leveraged copy of the stock.

Start with the underlying thesis, then test whether the contract is an efficient vehicle over that horizon.

## Understand the mechanism

Delta approximates the immediate directional response; Gamma changes it. Vega reprices the option when IV changes. Bid/ask spread, order size and changing quotes can outweigh a small modeled edge.

The displayed last trade is not necessarily an executable price for the desired side and quantity.

## Walk through the process

Read the contract, spread and liquidity before entry. Define the underlying invalidation, contract loss capacity and time-based exit. Avoid relying on market orders for precise small targets.

A position intended to close intraday still needs a plan for interruptions, failed fills and unexpected overnight exposure.

## 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

A fictional option has Delta 0.60, Gamma 0.04 and Vega 0.12 per IV point. Spot rises 0.50, contributing roughly 0.305 with Gamma. If IV falls two points, another approximately −0.24 leaves 0.065 per unit before time and execution.

A 0.10 round-trip execution disadvantage exceeds that modeled gain. The graph compares the common cash-unit contributions for 100 units. Being directionally right did not establish a profitable execution.

## Graph: Day trading options—worked comparison

**Horizontal:** Spot / IV / execution components  
**Vertical:** P/L contribution per 100 units (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-10.js` and displayed as an accessible table in the HTML lesson.

## What would invalidate the reading?

Watching only a green underlying candle ignores option repricing and costs. A stop on one market does not guarantee a precise fill in another.

## Check your understanding

### Does Delta-plus-Gamma 0.305 minus Vega loss 0.24 leave enough to cover 0.10 execution disadvantage?

**Answer:** No.

**Why:** 0.065 is smaller than 0.10.

### What is the critical failure to avoid?

**Answer:** Watching only a green underlying candle ignores option repricing and costs. A stop on one market does not guarantee a precise fill in another.

**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: Why can correct direction still produce a losing trade? 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)