Missing Data

Financial datasets are uneven. A valid symbol can have quotes but no options, history but sparse fundamentals, fundamentals but no analyst ratings, or a field that is present for one asset class and absent for another.

Missing Values

Treat missing data as part of the API contract.

Shape	Meaning
null	The field is known but no value is available for this symbol or time.
Empty array	The collection exists, but no rows matched the request.
Missing field	The field is not returned for that response shape.
404 / endpoint_not_found	The requested route or catalog endpoint is not available.
400 / bad_request	The request is malformed or missing a required parameter.

Invalid Symbols

An invalid or unsupported symbol can produce an empty result, a response with missing quote fields, or an error depending on the endpoint. For user-entered input, search first:

curl "https://api.yfin.dev/v1/search?q=appl" \
  -H "X-Yfin-Contact: you@example.com"

Then call quote or history with the selected symbol.

Defensive Handling

const quote = await client.quote(["AAPL"]);
const result = quote.data?.quoteResponse?.result?.[0];

if (!result?.regularMarketPrice) {
  // Show an unavailable state instead of displaying 0.
}

history = ticker.history(period="1mo", interval="1d")

if history.empty:
    print("No historical rows returned for this symbol and interval.")

Practical Rules

• Never convert missing price data to 0.
• Keep nullable fields nullable in your own types.
• Display "unavailable" instead of inventing fallback values for financial metrics.
• For optional datasets such as options, analyst ratings, sustainability, and SEC filings, handle empty results as normal behavior.
• Use Errors to distinguish malformed requests, rate limits, and temporary service failures.