Source: https://guthlabs.ai/docs/instruments/capm-expected-return/implementation/

instrument implementation / implementation-contract

# CAPM Expected Return implementation

A source-bound implementation contract for CAPM Expected Return; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t4-188

**Effect**: Computation or source lookup only

## Input and validation requirements

An extreme but syntactically numeric input produces a non-finite +Infinity result through floating-point overflow. A robust instrument should reject non-finite inputs or flag the non-finite output rather than display it as an expected return.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "risk_free_rate": 0.04,
    "beta": 1.2,
    "market_return": 0.1,
    "rate_unit": "decimal fraction"
  },
  "expected_outputs": {
    "expected_return_percent": 11.2
  },
  "working": "E(R) = 0.04 + 1.2 × (0.10 − 0.04) = 0.04 + 1.2 × 0.06 = 0.04 + 0.072 = 0.112 = 11.2%."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/capm-expected-return/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/capm-expected-return/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/capm-expected-return/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche4/tranche4-results.json`