# Moving Average Envelope

`D07-F07-A02` · Technical Indicators → Bands, Envelopes, and Squeezes · archetype `series-transform` · difficulty 2/5 · verification **verified**

Full page: https://docs.thefintechbuilder.com/technical-indicators/bands-envelopes-and-squeezes/moving-average-envelope/
Agent skill: `npx skills add IslamBaraka90/Fintech-Algorithms-Library` — https://docs.thefintechbuilder.com/guides/agent-skill/

## Install and import

```bash
npm install fintech-algorithms
```

```ts
import { movingAverageEnvelope } from "fintech-algorithms/technical-indicators/bands-envelopes-and-squeezes/moving-average-envelope";
```

## Signature

```ts
movingAverageEnvelope(input)
```

Moving Average Envelope: a simple moving average of close with bands set a fixed percentage above and below it.

## Parameters

| Name | Type | Required | Notes |
| --- | --- | --- | --- |
| `input` | `TopicInput` | yes | `bars` is the required OHLCV array -- each bar carries `timestamp`, `open`, `high`, `low`, `close`, `volume` and an optional `basis`, strictly ordered by timestamp. From `parameters` this topic reads `period` (default 20, integer >= 2), the moving-average window, and `percentage` (default 0.025, a finite number >= 0), the fractional envelope width. `period` (default 20, integer >= 2) and `multiplier` (default 2, a finite number >= 0) are read and validated by the band family for every topic in it. `multiplier` is not used by this branch. |

## Returns

`TopicResult`

`series` holds `center`, `upper` (`center * (1 + percentage)`) and `lower` (`center * (1 - percentage)`); `latest` carries the last of each. All three share a warm-up of `period - 1` leading nulls, so `ready_at` is 19 at the default period.

## Warm-up

The first ``period - 1` bars (19 at the default period)` positions are `null`. The envelope is a pure scaling of the centre line, so the bands become available on exactly the bar the moving average does.

## Errors

- When `parameters.percentage` is not a finite number, or is negative — throws Error
- When `parameters.period` is not an integer >= 2 — throws Error
- When a bar is missing open, high, low, close, or volume, or one of them is not a finite number — throws Error

## Complexity

Time `O(n * period)`, space `O(n)`.

## Worked example

Captured by running this function on the input its own test provides. Real output of real code — but not asserted against a published figure.

### Input

`input`:

```json
{
  "bars": [
    {
      "timestamp": "2024-01-02",
      "basis": "synthetic-unadjusted",
      "open": 100,
      "high": 101.45,
      "low": 98.695,
      "close": 100,
      "volume": 750000,
      "benchmark": 200
    },
    {
      "timestamp": "2024-01-03",
      "basis": "synthetic-unadjusted",
      "open": 101.49111452,
      "high": 103.38381693,
      "low": 100.05480022,
      "close": 101.78791214,
      "volume": 795117,
      "benchmark": 200.56326135
    },
    {
      "timestamp": "2024-01-04",
      "basis": "synthetic-unadjusted",
      "open": 102.45519048,
      "high": 104.6701838,
      "low": 100.91147007,
      "close": 102.9549389,
      "volume": 840234,
      "benchmark": 201.11020913
    }
  ],
  "parameters": {}
}
```

### Call

```ts
movingAverageEnvelope(input)
```

### Returns

object with 9 fields: topic_id, title, state, ready, ready_at, series, latest, parameters, …

```json
{
  "topic_id": "D07-F07-A02",
  "title": "Moving Average Envelope",
  "state": "calculated",
  "ready": true,
  "ready_at": 19,
  "series": {
    "center": [null, null, null, null, null, null],
    "upper": [null, null, null, null, null, null],
    "lower": [null, null, null, null, null, null]
  },
  "latest": {
    "center": 104.20055051999998,
    "upper": 106.80556428299997,
    "lower": 101.59553675699998
  },
  "parameters": {},
  "diagnostics": {
    "causal": true,
    "input_count": 96
  }
}
```

## Verification and provenance

Tier: **verified** (via E).

The worked example below is the figure published in this algorithm's article, replayed and asserted by the test suite on every build. The arithmetic cannot drift without the build failing.

Both tiers guarantee the signature. Full explanation: https://docs.thefintechbuilder.com/guides/verification/

Generated from the docs.json payload shipped inside fintech-algorithms@0.13.0.
The signature and parameter list are checked against the compiled implementation at build time,
so a description that contradicts the code fails the build rather than reaching this file.

## Links

- Article (how it works, step by step): https://thefintechbuilder.com/technical-indicators/bands-envelopes-and-squeezes/moving-average-envelope/
- Implementation source: https://github.com/IslamBaraka90/Fintech-Algorithms-Library/blob/main/src/technical-indicators/bands-envelopes-and-squeezes/moving-average-envelope/impl.ts
- Package on npm: https://www.npmjs.com/package/fintech-algorithms
- Domain index for agents: https://docs.thefintechbuilder.com/technical-indicators/llms.txt