Equity risk premium API reference

The equity risk premium and country risk premium by country

Overview

Narwhal's estimate of the equity risk premium: the extra return investors expect from shares over a risk-free government bond. Every request needs a Bearer key, and REST and MCP share one account quota.

A country is its ISO 3166 alpha-3 code, such as USA or IDN. The total is the mature market premium plus the country risk premium, and the country risk premium is the country default spread times the volatility ratio. Every figure is a percent as a decimal string with four places, except the ratio, which is a plain number.

Each figure carries its basis: observed from market or official data, modelled, or taken from a published country risk table that the method page cites. The method, inputs and limits are on the equity risk premium methodology page, and every answer links to it.

Base URL: https://api.narwhalapi.com. Each route below is an MCP tool of its own, with the same parameters.

Plans and limits

What	Free	Basic	Pro
Latest figure for a country	Included	Included	Included
Latest figure for every country	Included	Included	Included
History	Within the plan's history window	Within the plan's history window	Full history

See pricing for plan prices and monthly request limits. Each request counts as one call unless a route says otherwise.

A country appears only when we hold a row for it. Without a row the route returns 404 series_not_found; nothing is filled in or carried forward.
The mature market has no country premium: for the United States the default spread is 0, the volatility ratio is empty and the total equals the mature premium. Germany, the euro-area reference, also has a country premium of 0.
Figures are in US dollar terms. A discount rate in another currency needs the inflation difference between the two currencies added.
History is paged by date: send the next_cursor of a page, with the same other parameters, to read the next one.
The figures are estimates for analysis, not financial, investment, legal or tax advice.

Endpoints

Every route is a GET and needs your key in the Authorization: Bearer header. The examples show the shape of an answer, not live data.

Get a country's equity risk premium

GET /v1/economics/{country}/equity-risk-premium

The latest equity risk premium of one country, or the latest on or before date: the mature market premium, the country default spread, the volatility ratio, the country risk premium and the total, each with its basis.

Send date to read the latest figure on or before that day.

MCP: tool economics_get_equity_risk_premium.

Parameters

Parameter	Where	Required	Type	Meaning
`country`	path	Yes	string
`date`	query	No	string

Response fields

Field	Type	Sent
`country`	string	Always
`as_of`	date	Always
`unit`	always "percent"	Always
`mature_erp`	string	Always
`country_default_spread`	string	Always
`volatility_ratio`	string	Always
`country_risk_premium`	string	Always
`total_erp`	string	Always
`basis`	object	Always
`basis.mature_erp`	one of observed, modelled	Always
`basis.country_default_spread`	one of observed, modelled	Always
`basis.volatility_ratio`	one of observed, modelled	Always
`basis.country_risk_premium`	one of observed, modelled	Always
`basis.total_erp`	one of observed, modelled	Always
`methodology_url`	always "https://narwhalapi.com/methodology/equity-risk-premium"	Optional

curl -H "Authorization: Bearer $NARWHAL_API_KEY" \
  "https://api.narwhalapi.com/v1/economics/ITA/equity-risk-premium"

{
  "country": "ITA",
  "as_of": "2026-10-28",
  "unit": "percent",
  "mature_erp": "3.2230",
  "country_default_spread": "0.8881",
  "volatility_ratio": "2.0310",
  "country_risk_premium": "1.8037",
  "total_erp": "5.0267",
  "basis": {
    "mature_erp": "observed",
    "country_default_spread": "observed",
    "volatility_ratio": "modelled",
    "country_risk_premium": "modelled",
    "total_erp": "modelled"
  },
  "methodology_url": "https://narwhalapi.com/methodology/equity-risk-premium"
}

Get equity risk premium history

GET /v1/economics/{country}/equity-risk-premium/history

The equity risk premium of one country by date, oldest first, paged with next_cursor.

MCP: tool economics_get_equity_risk_premium_history.

Parameters

Parameter	Where	Required	Type	Meaning
`country`	path	Yes	string
`start`	query	No	string
`end`	query	No	string
`limit`	query	No	integer
`cursor`	query	No	string	`next_cursor` of the previous page, with the same other parameters.

Response fields

Field	Type	Sent	Meaning
`country`	string	Always
`observations`	list of object	Always
`observations[].country`	string	Always
`observations[].as_of`	date	Always
`observations[].unit`	always "percent"	Always
`observations[].mature_erp`	string	Always
`observations[].country_default_spread`	string	Always
`observations[].volatility_ratio`	string	Always
`observations[].country_risk_premium`	string	Always
`observations[].total_erp`	string	Always
`observations[].basis`	object	Always
`observations[].basis.mature_erp`	one of observed, modelled	Always
`observations[].basis.country_default_spread`	one of observed, modelled	Always
`observations[].basis.volatility_ratio`	one of observed, modelled	Always
`observations[].basis.country_risk_premium`	one of observed, modelled	Always
`observations[].basis.total_erp`	one of observed, modelled	Always
`observations[].methodology_url`	always "https://narwhalapi.com/methodology/equity-risk-premium"	Optional
`next_cursor`	string	Always	Pass as cursor to read the next page. Always sent; null on the last page.

curl -H "Authorization: Bearer $NARWHAL_API_KEY" \
  "https://api.narwhalapi.com/v1/economics/ITA/equity-risk-premium/history?start=2026-01-01"

{
  "country": "ITA",
  "observations": [
    {
      "country": "ITA",
      "as_of": "2026-09-01",
      "unit": "percent",
      "mature_erp": "3.2230",
      "country_default_spread": "0.8881",
      "volatility_ratio": "2.0310",
      "country_risk_premium": "1.8037",
      "total_erp": "5.0267",
      "basis": {
        "mature_erp": "observed",
        "country_default_spread": "observed",
        "volatility_ratio": "modelled",
        "country_risk_premium": "modelled",
        "total_erp": "modelled"
      },
      "methodology_url": "https://narwhalapi.com/methodology/equity-risk-premium"
    },
    {
      "country": "ITA",
      "as_of": "2026-10-28",
      "unit": "percent",
      "mature_erp": "3.2230",
      "country_default_spread": "0.8881",
      "volatility_ratio": "2.0310",
      "country_risk_premium": "1.8037",
      "total_erp": "5.0267",
      "basis": {
        "mature_erp": "observed",
        "country_default_spread": "observed",
        "volatility_ratio": "modelled",
        "country_risk_premium": "modelled",
        "total_erp": "modelled"
      },
      "methodology_url": "https://narwhalapi.com/methodology/equity-risk-premium"
    }
  ],
  "next_cursor": null
}

List equity risk premiums for all countries

GET /v1/economics/equity-risk-premium

The latest equity risk premium of every country that has one, sorted by country.

MCP: tool economics_list_equity_risk_premium.

Parameters

This route takes no parameters.

Response fields

Field	Type	Sent
`countries`	list of object	Always
`countries[].country`	string	Always
`countries[].as_of`	date	Always
`countries[].unit`	always "percent"	Always
`countries[].mature_erp`	string	Always
`countries[].country_default_spread`	string	Always
`countries[].volatility_ratio`	string	Always
`countries[].country_risk_premium`	string	Always
`countries[].total_erp`	string	Always
`countries[].basis`	object	Always
`countries[].basis.mature_erp`	one of observed, modelled	Always
`countries[].basis.country_default_spread`	one of observed, modelled	Always
`countries[].basis.volatility_ratio`	one of observed, modelled	Always
`countries[].basis.country_risk_premium`	one of observed, modelled	Always
`countries[].basis.total_erp`	one of observed, modelled	Always
`countries[].methodology_url`	always "https://narwhalapi.com/methodology/equity-risk-premium"	Optional

curl -H "Authorization: Bearer $NARWHAL_API_KEY" \
  "https://api.narwhalapi.com/v1/economics/equity-risk-premium"

{
  "countries": [
    {
      "country": "DEU",
      "as_of": "2026-10-28",
      "unit": "percent",
      "mature_erp": "3.2230",
      "country_default_spread": "0.0000",
      "volatility_ratio": "2.5462",
      "country_risk_premium": "0.0000",
      "total_erp": "3.2230",
      "basis": {
        "mature_erp": "observed",
        "country_default_spread": "observed",
        "volatility_ratio": "observed",
        "country_risk_premium": "observed",
        "total_erp": "observed"
      },
      "methodology_url": "https://narwhalapi.com/methodology/equity-risk-premium"
    },
    {
      "country": "ITA",
      "as_of": "2026-10-28",
      "unit": "percent",
      "mature_erp": "3.2230",
      "country_default_spread": "0.8881",
      "volatility_ratio": "2.0310",
      "country_risk_premium": "1.8037",
      "total_erp": "5.0267",
      "basis": {
        "mature_erp": "observed",
        "country_default_spread": "observed",
        "volatility_ratio": "modelled",
        "country_risk_premium": "modelled",
        "total_erp": "modelled"
      },
      "methodology_url": "https://narwhalapi.com/methodology/equity-risk-premium"
    }
  ]
}

Errors

Errors use the shared problem shape with a request_id. See Errors and quota for the shape and the quota headers. Failed requests are not charged.

Code	Status	Meaning
`invalid_query`	400	A parameter is missing, unknown, repeated or outside its range.
`series_not_found`	404	We hold no equity risk premium for this country.
`invalid_cursor`	400	The cursor is not one this request returned, or it comes from a different request.
`quota_exceeded`	429	Your plan has fewer calls left than the request needs.
`economics_unavailable`	503	The economics data cannot answer right now. Try again shortly.