> ## Documentation Index
> Fetch the complete documentation index at: https://docs.vintl.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Treasury Yield Curve

> Query daily treasury yield rates, build yield curves, and track the 10Y-2Y spread with the Vintl API.

The API serves daily U.S. Treasury yields from 1990 to present. Par curves cover 14 maturities (1M through 30Y). TIPS real yield curves cover 5 maturities from 2003. Treasury data is never revised — each day's rates are final.

## Rates by maturity

Fetch 10-year par yields for a date range:

<CodeGroup>
  ```bash cURL theme={"dark"}
  curl -H "X-API-Key: $VINTL_API_KEY" \
    "https://api.vintl.io/v1/treasury/yields?maturity=10Y&from=2026-01-01&to=2026-03-24"
  ```

  ```python Python theme={"dark"}
  import os, requests

  resp = requests.get(
      "https://api.vintl.io/v1/treasury/yields",
      headers={"X-API-Key": os.environ["VINTL_API_KEY"]},
      params={"maturity": "10Y", "from": "2026-01-01", "to": "2026-03-24"}
  )
  for rate in resp.json()["results"]:
      print(f"{rate['trade_date']}: {rate['rate']}%")
  ```

  ```typescript TypeScript theme={"dark"}
  const resp = await fetch(
    "https://api.vintl.io/v1/treasury/yields?maturity=10Y&from=2026-01-01&to=2026-03-24",
    { headers: { "X-API-Key": process.env.VINTL_API_KEY! } }
  );
  const data = await resp.json();
  data.results.forEach((r: any) => console.log(`${r.trade_date}: ${r.rate}%`));
  ```
</CodeGroup>

Available maturities: `1M`, `2M`, `3M`, `4M`, `6M`, `1Y`, `2Y`, `3Y`, `5Y`, `7Y`, `10Y`, `20Y`, `30Y`.

## Full yield curve

Fetch all maturities for a single date:

```bash theme={"dark"}
curl -H "X-API-Key: $VINTL_API_KEY" \
  "https://api.vintl.io/v1/treasury/yields/curve?date=2026-03-24"
```

Returns one row per maturity, sorted shortest to longest. Use this to plot the curve or detect inversions.

## The 10Y-2Y spread

The spread endpoint calculates the difference between two maturities:

```bash theme={"dark"}
curl -H "X-API-Key: $VINTL_API_KEY" \
  "https://api.vintl.io/v1/treasury/yields/spread?long=10Y&short=2Y&from=2025-01-01"
```

```json Response theme={"dark"}
{
  "object": "spread_series",
  "results": [
    {
      "trade_date": "2026-03-24T00:00:00Z",
      "long_rate": "4.39",
      "short_rate": "3.90",
      "spread_bps": "49.00",
      "long_maturity": "10Y",
      "short_maturity": "2Y"
    }
  ]
}
```

`spread_bps` is in basis points. Positive = normal curve, negative = inverted. The 10Y-2Y spread inverted before every U.S. recession since 1970.

You can compare any two maturities — `long=30Y&short=5Y`, `long=10Y&short=3M`, etc.

## TIPS real yields

Pass `curve_type=TIPS` for inflation-adjusted yields:

```bash theme={"dark"}
curl -H "X-API-Key: $VINTL_API_KEY" \
  "https://api.vintl.io/v1/treasury/yields?maturity=10Y&curve_type=TIPS&limit=5"
```

TIPS data covers 5Y, 7Y, 10Y, 20Y, and 30Y from 2003 onward. The spread between par and TIPS yields at the same maturity approximates the market's inflation expectation (breakeven inflation rate).