# US Treasury Par Yield Curve (CMT Rates)

> US Treasury Par Yield Curve (CMT Rates) is a paid API for AI agents from x402stock.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).

Returns the daily US Treasury par yield curve (Constant Maturity Treasury rates) for all maturities from 1 month to 30 years, in percent.

## Facts

- Endpoint: GET https://x402stock.vercel.app/api/v1/treasury-yields
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/us-treasury-par-yield-curve-cmt-rates-2cf3af3f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_pF-5l0JoUmI24We61SNVP

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability us-treasury-par-yield-curve-cmt-rates-2cf3af3f
```

Example prompt: Pull the latest US Treasury par yield curve — all maturities from 1 month to 30 years — so I can check if the curve is inverted and grab the risk-free rate for my valuation model.

## When to prefer this

Use this endpoint when you need authoritative US Treasury CMT rates for risk-free rate inputs, yield curve shape analysis (inversion detection), interest rate sensitivity context, or macro-aware financial modeling — without needing any stock ticker or security identifier. Prefer over scraping Treasury.gov or using stale cached data.

## Known failure modes

- Invalid year parameter outside 1990-2100 range returns validation error
- Limit exceeding 250 returns error; limit must be a positive integer
- No data available for requested year (e.g. future year) returns empty or null
- Rate limiting or payment failure returns 402 payment required
- Treasury data may lag by one business day; weekends/holidays return last published day

## How this service works

The daily US Treasury par yield curve (Constant Maturity Treasury rates) for every maturity from 1 month to 30 years, in percent. Defaults to the latest published day; pass `?limit=` for more recent days (max 250) and `?year=YYYY`. No ticker needed. Use for the risk-free rate, rate-sensitivity context, and yield-curve inversion in macro-aware analysis. From x402stock

## Output

Returns an array of dated records, each containing CMT yield rates (in percent) keyed by maturity label (e.g. '1M', '3M', '2Y', '10Y', '30Y'), along with metadata including source ('us_treasury'), as_of date, list of maturities, unit ('percent'), and count of records returned.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "$schema": "https://json-schema.org/draft/2020-12/schema",
     "required": [
      "limit"
     ],
     "properties": {
      "year": {
       "type": "integer",
       "maximum": 2100,
       "minimum": 1990
      },
      "limit": {
       "type": "integer",
       "default": 1,
       "maximum": 250,
       "exclusiveMinimum": 0
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "$schema": "https://json-schema.org/draft/2020-12/schema",
     "required": [
      "source",
      "as_of",
      "series",
      "unit",
      "maturities",
      "count",
      "rates"
     ],
     "properties": {
      "unit": {
       "type": "string"
      },
      "as_of": {
       "anyOf": [
        {
         "type": "string"
        },
        {
         "type": "null"
        }
       ]
      },
      "count": {
       "type": "number"
      },
      "rates": {
       "type": "array",
       "items": {
        "type": "object",
        "required": [
         "date",
         "rates"
        ],
        "properties": {
         "date": {
          "type": "string"
         },
         "rates": {
          "type": "object",
          "propertyNames": {
           "type": "string"
          },
          "additionalProperties": {
           "anyOf": [
            {
             "type": "number"
            },
            {
             "type": "null"
            }
           ]
          }
         }
        },
        "additionalProperties": false
       }
      },
      "series": {
       "type": "string"
      },
      "source": {
       "type": "string",
       "const": "us_treasury"
      },
      "maturities": {
       "type": "array",
       "items": {
        "type": "string"
       }
      }
     },
     "additionalProperties": false
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/us-treasury-par-yield-curve-cmt-rates-2cf3af3f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402stock.vercel.app](https://www.zero.xyz/host/x402stock.vercel.app/llms.txt)