Source: https://guthlabs.ai/docs/instruments/dividend-yield-growth-ddm/implementation/

instrument implementation / implementation-contract

# Dividend Yield & Growth (DDM) implementation

A source-bound implementation contract for Dividend Yield & Growth (DDM); 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**: t4-212

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification provides no stated rejection behavior for r = g or r < g. Literal arithmetic produces an undefined result at r = g and an economically invalid negative value when r < g. The dividend D0-versus-D1 convention is also unspecified, producing different fair values.

## 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": {
    "price": 50,
    "annual_div": 2,
    "dividend": 2,
    "growth_rate": 0.03,
    "required_return": 0.08
  },
  "expected_outputs": {
    "yield_percent": 4,
    "ddm_fair_value": 40
  },
  "working": "Yield = annual_div / price = 2 / 50 = 0.04. Convert to percent: 0.04 * 100 = 4%. Gordon value = D1 / (r - g) = 2 / (0.08 - 0.03) = 2 / 0.05 = 40."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/dividend-yield-growth-ddm/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/dividend-yield-growth-ddm/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/dividend-yield-growth-ddm/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`