# Margin and cash survival

**FUT-21 · Equity Index Futures · Core**

**Lesson question:** Why can an eventual correct view still fail?

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:** FUT-01

Futures margin supports performance obligations; it is not the maximum loss. Daily settlement and broker risk controls can require cash before a hoped-for recovery arrives.

A view can be eventually correct while the account cannot finance the path.

## Understand the mechanism

Initial, maintenance and broker house requirements vary with product and conditions. The balances in this lesson are invented to illustrate a cash constraint, not current margin quotes.

Mark-to-market separates daily transfers from eventual cumulative P/L. A later gain cannot fund an earlier requirement retroactively.

## Walk through the process

Stress the interim cash path and potential changes in requirements. Know the actual liquidation agreement and funding access. Do not assume a broker will wait for a recovery.

Size from tolerable loss and liquidity, not from the lowest displayed deposit.

## Operational boundary

All figures are fictional teaching inputs, not current quotes or margin schedules. Product rules, broker requirements and usable liquidity remain separate from the model example. A planned exit and an algebraic hedge are not execution guarantees.

## A worked example

A fictional account allocates 10,000 to one 50-dollar-point long at 5,000. Settlement at 4,980 creates a 1,000 loss, leaving 9,000 before other items. If this invented scenario's maintenance requirement is 9,500, the balance is insufficient.

The graph varies adverse points and the remaining cash. The account requirements are hypothetical; the arithmetic shows why monitoring the funding path matters.

## Graph: Margin and cash survival—worked comparison

**Horizontal:** Adverse price change (points)  
**Vertical:** Hypothetical cash remaining (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/equity-futures/FUT-21.js` and displayed as an accessible table in the HTML lesson.

## What would invalidate the reading?

Treating the original deposit as a loss ceiling or relying on a rebound can lead to liquidation or a deficit.

## Check your understanding

### What does a twenty-point loss cost at fifty dollars per point?

**Answer:** 1,000.

**Why:** Actual account consequences depend on its rules.

### What is the critical failure to avoid?

**Answer:** Treating the original deposit as a loss ceiling or relying on a rebound can lead to liquidation or a deficit.

**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 an eventual correct view still fail? 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.

- [CME Mark-to-Market](https://www.cmegroup.com/education/courses/introduction-to-futures/mark-to-market)

- [CME Introduction to Futures](https://www.cmegroup.com/education/courses/introduction-to-futures)