---
title: "Compare letter topics"
method: GET
path: "/v1/fund-letters/diff"
tags: ["Fund Letters"]
---

# Compare letter topics

`GET /v1/fund-letters/diff`

## Request

- Base URL: `https://api.turos.app`
- URL: `https://api.turos.app/v1/fund-letters/diff`
- Auth: one of:
  - API key in header `x-api-key`
  - HTTP bearer

Identify letters by from_letter_id + to_letter_id, or by issuer_cik / issuer_ticker plus from_period + to_period. Deterministic lexicon in v1; no public sentiment field. Metered as fund_letter_lookup.

## Query parameters

- `from_letter_id` string
- `to_letter_id` string
- `issuer_cik` string
- `issuer_ticker` string
- `from_period` string
- `to_period` string

## Response `200`

Successful response

- FundLetterTopicDiff
  - `object` 'fund_letter_topic_diff', required
  - `fromLetterId` string, required
  - `toLetterId` string, required
  - `extractorVersion` string, required
  - `chips` object[], required
    - `topic` 'ai' | 'headcount' | 'capital_allocation' | 'insurance_float' | 'square_gpv' | 'cash_app' | 'regulation' | 'buybacks' | 'leadership', required
    - `change` 'appeared' | 'intensified' | 'vanished', required
    - `fromMentions` object[], required
      - `page` integer, required
      - `charStart` integer, required
      - `charEnd` integer, required
      - `quote` string, required
      - `sourceSha256` string, required
      - `paginationVersion` string, required
      - `topic` 'ai' | 'headcount' | 'capital_allocation' | 'insurance_float' | 'square_gpv' | 'cash_app' | 'regulation' | 'buybacks' | 'leadership', required
    - `toMentions` object[], required
      - `page` integer, required
      - `charStart` integer, required
      - `charEnd` integer, required
      - `quote` string, required
      - `sourceSha256` string, required
      - `paginationVersion` string, required
      - `topic` 'ai' | 'headcount' | 'capital_allocation' | 'insurance_float' | 'square_gpv' | 'cash_app' | 'regulation' | 'buybacks' | 'leadership', required

## Other responses

- `default`: Contract-aware error response

---

[API](https://skmtc.dev/turos/apis/turos-api.md) · [All operations](https://skmtc.dev/turos/apis/turos-api/llms.txt) · [OpenAPI document](https://skmtc.dev/turos/apis/turos-api/revisions/a68d3ec80a56?raw)