---
title: "GSW fitted nominal Treasury curve"
method: GET
path: "/api/v2/fixed-income/treasury/gsw-curve"
tags: ["Fixed Income"]
---

# GSW fitted nominal Treasury curve

`GET /api/v2/fixed-income/treasury/gsw-curve`

The Federal Reserve Board GSW (Gurkaynak-Sack-Wright) fitted nominal Treasury yield curve for one day: zero-coupon, par, and instantaneous forward rates at 1Y-30Y, plus the 1y1y and 5y5y forwards. Omit date for the latest published curve (weekly, may lag a few business days), or pass date (YYYY-MM-DD) for on or before. NOTE: a Federal Reserve staff research product, NOT an official statistical release - subject to delay, revision, or methodology change without advance notice.

## Query parameters

- `date` string, nullable — Curve date (YYYY-MM-DD). Omit for latest.

## Response `200`

Zero / par / forward points for the GSW nominal curve.

- EnvelopeGswCurveData
  - `data` GswCurveData, required — The Federal Reserve Board GSW fitted nominal Treasury curve for one day. A staff research product, NOT an official Federal Reserve statistical release - subject to delay, revision, or methodology change without advance notice.
    - `date` string, required — Curve date (weekly-published, may lag a few business days).
    - `points` GswCurvePoint[], required
      - `tenor` string, required
      - `tenor_months` number, required
      - `zero_yield` number, nullable — Zero-coupon yield, continuously compounded (SVENYxx).
      - `par_yield` number, nullable — Par yield, coupon-equivalent (SVENPYxx).
      - `inst_forward` number, nullable — Instantaneous forward rate, continuously compounded (SVENFxx).
    - `forward_1y1y` number, nullable — 1-year forward 1-year rate, coupon-equivalent (SVEN1F01).
    - `forward_5y5y` number, nullable — 5-year forward 5-year zero rate, derived from SVENY05/SVENY10.
  - `meta` SugraMeta, required — Metadata attached to every /api/v1/* response envelope.
    - `endpoint` string, required — Requested endpoint path.
    - `data_time` string, required — ISO 8601 UTC timestamp of the source data, not of the request.
    - `response_time` string, required — ISO 8601 UTC timestamp when this response was produced.
    - `provider` string, required — API name and version.
    - `source` string, nullable — Identifier of the primary upstream source used for this response.
    - `attribution` string, nullable — Human-readable attribution mandated by an upstream source (e.g. a securities regulator or self-regulatory organization). Present only on responses whose source requires the owner and source to be clearly identified. Do not remove or alter it when using the response.
    - `fallback_used` boolean, nullable — True when the primary source failed and a fallback produced the data.
    - `fallback_chain` string[], nullable — Ordered list of sources attempted, in the order they were tried.
    - `cached` boolean, nullable — True when this response was served from the internal cache.
    - `stale` boolean, nullable — True when the cached response was returned after the upstream rate-limited or errored. Clients can use this to detect degraded data.

## Other responses

- `401` — Missing or invalid `x-api-key` header. JSON body with a stable `code` distinguishing `missing_api_key` (no header sent) from `invalid_api_key` (header sent, key not accepted); any other 401 source carries the generic `unauthorized` with its detail as `reason`. Plus `hint`. `plan` is always null on 401 - an unauthenticated request has no plan; quota exhaustion is 429, not 401.
- `422` — Validation Error
- `429` — Daily rate limit exceeded. Check `X-RateLimit-Reset` for the next window.
- `503` — Upstream source is temporarily unavailable. Retry after a short delay.

---

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