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4 Month Treasury Yield API

The 4-month (17-week) CMT par yield.

Retrieve the 4 Month Treasury yield programmatically with the Treasury Yield API. The current value is available on the full yield curve, and the complete history is available as a time series using the month_4 maturity code.

As of the latest reading, the 4 Month Treasury par yield was 3.91%. Data is sourced from the U.S. Department of the Treasury and updated every business day.

Current 4 Month yield

The 4 Month rate is included in the current yield curve from /v1/treasuryyield (field month_4 in rates):

{
  "date": "2026-08-10",
  "type": "par",
  "maturity": "month_4",
  "rate_pct": 3.91
}

Historical 4 Month yield

Get the 4 Month time series from /v1/treasuryyieldhistorical?maturity=month_4:

{
  "type": "par",
  "maturity": "month_4",
  "data": [
    {
      "date": "2026-08-05",
      "rate_pct": 3.94
    },
    {
      "date": "2026-08-06",
      "rate_pct": 3.92
    },
    {
      "date": "2026-08-07",
      "rate_pct": 3.89
    },
    {
      "date": "2026-08-10",
      "rate_pct": 3.91
    }
  ]
}

Related

  • Treasury Yield API — full curve (par, real/TIPS, and bill rates) plus 2s10s / 3m10s spreads.
  • Interest Rate API — central bank policy rates and benchmark rates (SOFR, EURIBOR).
(4.1)

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Applications using this API

API Status

Online - All Systems Operational

API Response Times

Average
P50
P75
P90
P95
344ms376ms387ms753ms998ms

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Code Examples

1 2 curl -X GET "https://api.api-ninjas.com/v1/treasuryyieldhistorical?maturity=month_4" \ -H "X-Api-Key: YOUR_API_KEY"

Frequently Asked Questions

  • Yes, but you must have a premium subscription. Commercial use of the Treasury Yield API is not permitted on the free tier. See our pricing page to choose a plan that fits your needs.
  • Sign up for a free account to instantly get your API key, then pass it in the X-Api-Key header on every request. The documentation above includes ready-to-run examples in cURL, Python, JavaScript, Node.js, and more.
  • Your API requests will simply be denied once you hit your monthly quota — you will never be charged more than the plan you signed up for. To increase your quota, you can upgrade your plan any time on our pricing page.
  • The API responds with a standard HTTP status code and a JSON error message describing the problem. See our error codes reference for the full list of codes and how to resolve each one, or contact support if you need help.