# Call walls and put walls

**DL-07 · Dealer Logic · Core**

**Lesson question:** What does the provider's wall label measure?

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:** DL-01

Call wall and put wall are practitioner or vendor terms, not uniform exchange definitions. One service can mean largest OI; another can mean largest modeled Gamma contribution. Their identical labels need not describe identical economics.

## Understand the mechanism

Useful metadata include included expiries, timestamps, position assumptions and units. Contract count, dollar Gamma and traded premium are different measures. Positions can also roll or close.

A call concentration is not automatically resistance and a put concentration is not automatically support. Their possible effects depend on signed inventory and actual hedging.

## Walk through the process

Read methodology first, then observe whether price rejects, accepts or passes through the area. Keep the line's instrument separate from an ETF or futures proxy.

If price contradicts the interpretation, reassess the model. Do not claim the tape is wrong because it crossed a labeled wall.

## Evidence boundary

The arithmetic is original conditional teaching material, not a measurement of current dealer positions. The cited Cboe research is historical product-specific evidence, not a live inventory feed. Model outputs should remain distinguishable from observed market facts.

## A worked example

A fictional service marks 105 as a call wall based on its largest included OI. Price subsequently trades 104.80, 105.10, 105.40 and 105.60, building activity above the line.

Under a sustained-acceptance interpretation, simple resistance did not hold. That observation does not prove a dealer changed intent; it only challenges the initial hypothesis.

## Graph: Call walls and put walls—worked comparison

**Horizontal:** Completed observation  
**Vertical:** Spot (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/dealer-logic/DL-07.js` and displayed as an accessible table in the HTML lesson.

## What would invalidate the reading?

An automatic trade on a wall assumes both a definition and a force that may not exist. Raw levels from different instruments can also create false confluence.

## Check your understanding

### What must be matched before comparing two wall providers?

**Answer:** Measures, included contracts, timestamps and position assumptions.

**Why:** The label alone is not a common specification.

### What is the critical failure to avoid?

**Answer:** An automatic trade on a wall assumes both a definition and a force that may not exist. Raw levels from different instruments can also create false confluence.

**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 does the provider's wall label measure? 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.

- [OIC Greeks](https://www.optionseducation.org/advancedconcepts/understanding-options-greeks)

- [Cboe 0DTE positioning study, May 2025](https://www.cboe.com/insights/posts/0-dt-es-decoded-positioning-trends-and-market-impact)