# Mercury402 Treasury Yield Curve Historical Data

> Mercury402 Treasury Yield Curve Historical Data is a paid API for AI agents from mercury402.uk, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).

Returns historical US Treasury yield curve data for a specified date range

## Facts

- Endpoint: POST https://mercury402.uk/v1/treasury/yield-curve/historical
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/mercury402-treasury-yield-curve-historical-data-6e02bb88
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_0-vJZbwd8E7E9247HbDpf

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 mercury402-treasury-yield-curve-historical-data-6e02bb88 -d '<json body>'
```

Example prompt: Can you pull the historical US Treasury yield curve data from January 1, 2024 through March 31, 2024 so I can see how rates evolved across the curve over that quarter?

## When to prefer this

Use this endpoint when you need historical US Treasury yield curve data for a specific date range — ideal for macro analysis, backtesting, interest rate modeling, or studying yield curve inversion/steepening events. Prefer this over real-time endpoints when analyzing past rate environments or doing quantitative research across a window of time.

## Known failure modes

- Invalid or malformed date format returns error
- start_date after end_date causes bad request
- Date range too large may return empty or partial data
- Payment not included or insufficient USDC causes 402 rejection
- No data available for future or very old dates returns empty array

## How this service works

76 live pay-per-call financial data APIs for AI agents. Treasury, FRED, forex, spreads, breakeven inflation, macro bundles, and composite dashboards. USDC on Base.

## Output

A JSON object containing an array of historical yield curve data points indexed by date, along with the start_date and end_date of the requested range. Each data entry represents Treasury yields across maturities for that period.

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": [],
  "end_date": "2024-03-31",
  "start_date": "2024-01-01"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/mercury402-treasury-yield-curve-historical-data-6e02bb88/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mercury402.uk](https://www.zero.xyz/host/mercury402.uk/llms.txt)