How do I get the volatility and Sharpe ratio of a fund by ISIN?

Where it is in the response

Sample for iShares Core MSCI World UCITS ETF (IE00B4L5Y983):

json
"headlineMetrics": { "volatility3y": "11.8%", "sharpe3y": "1.68" },
"metrics": { "maxDrawdown": "-16.5%" }

Where the figure comes from

Where the fund house prints its own figures they are returned as published; otherwise they are computed from its total-return history over the last 36 complete months (volatility of monthly returns annualised, Sharpe ratio over a same-currency money-market fund, none for money-market funds). The freshness page states the formulas, and this guide shows how to recompute them from indexedPerformance.points.

The request

bash
curl -s --max-time 300 https://fundfactsapi.com/api/v1/funds/IE00B4L5Y983 \
  -H "Authorization: Bearer $FUNDFACTS_API_KEY" | jq '.data.headlineMetrics | {volatility3y, sharpe3y}'

python
import os, requests
r = requests.get("https://fundfactsapi.com/api/v1/funds/IE00B4L5Y983",
                 headers={"Authorization": f"Bearer {os.environ['FUNDFACTS_API_KEY']}"}, timeout=300)
fund = r.json()
print(fund["name"], fund['data']['headlineMetrics']['volatility3y'])

javascript
const res = await fetch("https://fundfactsapi.com/api/v1/funds/IE00B4L5Y983", {
  headers: { Authorization: `Bearer ${process.env.FUNDFACTS_API_KEY}` },
  signal: AbortSignal.timeout(300_000),
});
const fund = await res.json();
console.log(fund.name, fund.data.headlineMetrics.volatility3y);

Sign up at fundfactsapi.com/signup for a key; the Free plan is 5 lookups a month with no card. Without a key, GET https://fundfactsapi.com/api/v1/demo/funds/IE00B4L5Y983 returns the same payload for funds already in the store (30 calls a minute per IP; it never loads a new fund).

Caveats

• Funds younger than three years return empty strings; check keyFacts.inception.
• Sharpe ratios computed by different providers differ with the risk-free rate they assume; compare funds within one source.

Several funds at once

POST /funds with { "isins": ["…", "…"], "wait": true } returns the same payload for up to 10 ISINs per call on Starter, 50 on Pro and 200 on Scale. One request is counted per fund found. X-RateLimit-Remaining on every response tells you how many are left this month; a 429 rate_limited response carries Retry-After. Search and /me are free.

A fund never loaded before is read on demand from the documents the fund house publishes. That first call takes 15 seconds to about 3 minutes; set your client timeout to 300 seconds and do not fire a second request for the same ISIN while the first is running. Every later call returns from the store in well under a second with cached: true; past 24 hours the payload comes back flagged stale: true while a refresh runs in the background, and nothing older than 7 days is served without a new read.

Everything else in the payload is listed in the field reference.