# Intraday Index-Level Calculation

`D03-F01-A05` · Index and Benchmark Engineering → Index Initialization and Continuity · archetype `record-transform` · difficulty 3/5 · verification **verified**

Full page: https://docs.thefintechbuilder.com/index-and-benchmark-engineering/index-initialization-and-continuity/intraday-index-level-calculation/
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 { calculate } from "fintech-algorithms/index-and-benchmark-engineering/index-initialization-and-continuity/intraday-index-level-calculation";
```

## Signature

```ts
calculate(data)
```

Recomputes the level from a live price snapshot using fixed index shares and float factors. Shares and float are held constant through the session — only prices move — which is why an intraday level is cheap to compute.

## Parameters

| Name | Type | Required | Notes |
| --- | --- | --- | --- |
| `data` | `{ indexShares: Record<string, number>; floatFactors: Record<string, number>; divisor: number; snapshots: Snapshot[] }` | yes | `indexShares` and `floatFactors` are set at the last rebalance, not recalculated per tick. `snapshots` are the price updates to evaluate. |

## Returns

`{ levels, divisor }`

A level per snapshot, and the divisor used.

## Errors

- When a snapshot references a constituent with no index shares — throws

## Complexity

Time `O(snapshots × constituents)`, space `O(snapshots)`.

## Worked example

This is the worked example published in the article, replayed by the test suite on every run. The output cannot drift.

### Input

`data`:

```json
{
  "indexShares": [800, 450, 1080],
  "floatFactors": [1, 1, 1],
  "divisor": 120,
  "snapshots": [
    {
      "timestamp": "09:30",
      "prices": [50, 80, 40],
      "fxRates": [1, 1, 1]
    },
    {
      "timestamp": "10:00",
      "prices": [50.5, 79, 40.2],
      "fxRates": [1, 1, 1]
    },
    {
      "timestamp": "10:30",
      "prices": [51, 79.5, 40.6],
      "fxRates": [1, 1, 1]
    }
  ]
}
```

### Call

```ts
calculate(data)
```

### Returns

object with 2 fields: levels, divisor

```json
{
  "levels": [
    {
      "timestamp": "09:30",
      "numerator": 119200,
      "level": 993.333333
    },
    {
      "timestamp": "10:00",
      "numerator": 119366,
      "level": 994.716667
    },
    {
      "timestamp": "10:30",
      "numerator": 120423,
      "level": 1003.525
    }
  ],
  "divisor": 120
}
```

## Verification and provenance

Tier: **verified** (via input-expected).

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@0.13.1.
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/index-and-benchmark-engineering/index-initialization-and-continuity/intraday-index-level-calculation/
- Implementation source: https://github.com/IslamBaraka90/Fintech-Algorithms-Library/blob/main/src/index-and-benchmark-engineering/index-initialization-and-continuity/intraday-index-level-calculation/impl.ts
- Package on npm: https://www.npmjs.com/package/fintech-algorithms
- Domain index for agents: https://docs.thefintechbuilder.com/index-and-benchmark-engineering/llms.txt