# Apparent cash/futures disagreement

**FUT-25 · Equity Index Futures · Core**

**Lesson question:** What should be checked before declaring mispricing?

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

A large apparent gap can be economic or a measurement mismatch. Different timestamps, contract months, adjustment methods and carry all change the comparison.

The first response to surprising divergence should often be a data audit.

## Understand the mechanism

A cash index can be stale while a future trades currently. The next-quarter quote can differ from the front month. A back-adjusted history can display levels never quoted by one actual contract.

Arbitrage relates comparable economic claims, not every pair of numbers on two screens.

## Walk through the process

Check symbol, month, source delay, time zone, adjustment method and fair-value convention. Compare synchronized observations and report missing or delayed data.

Only then consider an economic explanation. An apparent precise live signal built from stale data is not precise evidence.

## 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

Cash shows 5,000 from fifteen minutes earlier. The current near future is 5,035 and the next month 5,060. Comparing next month with stale cash gives a sixty-point gap.

If current synchronized cash is 5,020 and near fair basis fifteen points, the near future is consistent with the snapshot. The graph exposes the distinct references rather than mixing them.

## Graph: Apparent cash/futures disagreement—worked comparison

**Horizontal:** Stale cash / current cash / near future / next future  
**Vertical:** Quoted level

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-25.js` and displayed as an accessible table in the HTML lesson.

## What would invalidate the reading?

A chart that rolled months can create false divergence. Selling a supposed premium without aligning inputs can trade a data error.

## Check your understanding

### What should be aligned before interpreting the gap?

**Answer:** Time, contract month, underlying definition, adjustment and carry.

**Why:** A data audit is part of analysis.

### What is the critical failure to avoid?

**Answer:** A chart that rolled months can create false divergence. Selling a supposed premium without aligning inputs can trade a data error.

**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 should be checked before declaring mispricing? 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 Introduction to Futures](https://www.cmegroup.com/education/courses/introduction-to-futures)

- [CME Micro E-mini overview](https://www.cmegroup.com/education/courses/micro-e-mini-futures/micro-e-mini-futures-products-overview)