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📈 Yahoo Finance Provider (yfinance)

The Yahoo Finance provider fetches stock, ETF, crypto, and index prices using the yfinance library. It is the primary market data provider for LibreFolio.

Implementation: backend/app/services/asset_source_providers/yahoo_finance/plugin.py

📖 User Guide: Yahoo Finance — User Manual

⚙️ How it Works

  1. Identifier: A Yahoo Finance ticker symbol (e.g., AAPL, BTC-USD, IE00B4L5Y983).
  2. Identifier Types: TICKER and ISIN are both accepted. ISIN is resolved by yfinance internally.
  3. No provider_params: Yahoo Finance does not require any additional configuration.

💰 Current Value (get_current_value)

  1. The asset-source service checks its core current-value cache (120s TTL) before invoking the provider.
  2. Calls ticker.info — the Yahoo quoteSummary endpoint. Returns regularMarketPrice, currency, and regularMarketTime in a single lightweight call.
  3. Fallback price: currentPrice → previousClose (if regularMarketPrice is null).
  4. No history() call at all — current value polling never touches the chart API.

Avoid history() and fast_info for current price

  • ticker.history() calls the chart API and logs noisy Entering history() lines.
  • ticker.fast_info internally triggers 2 heavy HTTP calls (range=1y + range=5d).
  • ticker.info uses the quoteSummary endpoint — lighter, returns price + currency together.

Cache TTL vs Polling Interval

Frontend polls every 30s for responsive UI, while the core cache has a 120s TTL. Repeated polls for the same provider key can therefore return without another Yahoo call.

📈 Historical Data (get_history_value)

The public method now delegates its local work to focused helpers without changing its contract:

  1. Acquire — _acquire_history_data()
  2. start_date == "min" calls ticker.history(period="max").
  3. A finite range calls ticker.history(start=start_date, end=end_date + 1 day), preserving LibreFolio's inclusive end date over yfinance's exclusive end.
  4. Currency metadata falls back to USD.
  5. Dividend and split series are acquired independently and best-effort; one failing does not suppress the other or the prices.
  6. Map — _map_history_prices()
  7. Yahoo index values are converted to UTC before extracting the calendar date.
  8. Rows are filtered to the requested inclusive range.
  9. A row with Close = NaN is skipped. Optional Open, High, Low, or Volume NaNs become None.
  10. The provider returns only actual trading days; the query layer performs backward fill.
  11. Events — _parse_dividend_events() and _parse_split_events()
  12. Positive in-range dividends and non-trivial in-range split ratios become typed asset events.
  13. The two parsers are also isolated best-effort, so either event family can survive a failure in the other.

Validation and data failures remain typed AssetSourceErrors: unsupported identifier types use INVALID_IDENTIFIER_TYPE, a missing optional dependency uses NOT_AVAILABLE, empty/unusable history uses NO_DATA, and malformed or unexpected Yahoo responses use FETCH_ERROR.

No provider-internal thread hop

Yahoo's yfinance calls remain synchronous and direct. The provider does not call asyncio.to_thread(); the asset-source service invokes the whole provider coroutine through asset_sources.core._run_provider_in_thread() in a dedicated thread with a new event loop.

  • Uses yfinance.Search(query) for real-time ticker search.
  • Minimum query length: 2 characters.
  • Results limited to top 20 quotes.
  • quoteType is normalized to LibreFolio asset types: equity → STOCK, etf → ETF, mutualfund → FUND, cryptocurrency → CRYPTO, etc.
  • Currency is fetched per-symbol via _fetch_currency() (cached separately, 24-hour TTL).

📋 Metadata (fetch_asset_metadata)

  • Fetches full ticker.info from Yahoo Finance.
  • Extracts: asset_type, currency, short_description (from longBusinessSummary), sector (single-sector distribution), identifier_ticker, identifier_isin.
  • ISIN is obtained via ticker.isin (not available for all markets).
  • Unknown sectors are logged as warnings and mapped to "Other".

🔗 get_asset_url

Returns https://finance.yahoo.com/quote/{identifier}.

📅 Asset Events

During sync, the provider generates:

  • DIVIDEND events from ticker.dividends — ex-dividend date + per-share amount.
  • SPLIT events from ticker.splits — split date + ratio value (e.g., 4.0 for a 4:1 split).

Event acquisition and parsing are best-effort and independent. Events that are returned are persisted by asset_sources/price_store.py::_upsert_asset_events(), keyed by provider_assignment_id.

⚡ Caching Strategy

Owner / Cache Key TTL Max Size Purpose
Core current value Provider code + identifier + identifier type (refresh also includes the provider-parameter hash) 120 sec 300 Avoid repeated ticker.info calls during current-price polling and refresh.
Core history Provider code + identifier + identifier type + provider-parameter hash 15 min 500 Reuse fetched date ranges during provider-driven refresh.
Core search query Provider code + normalized query 15 min 500 Avoid repeating the same provider search.
Yahoo currency lookup symbol 24 hours 2000 Cache the provider's fast_info currency sub-operation used by search().

All are in-memory, per-process TTL caches created with get_ttl_cache(). The shared result caches are owned by asset_sources/core.py; Yahoo owns only its currency sub-operation cache.

No provider-level history cache

Yahoo has no provider-level history cache. The outer refresh layer may reuse its core history cache and persists fetched prices to the database. get_prices_bulk() is DB-only; it never calls Yahoo while serving a historical query (see Architecture — Price Query).

🧪 Test Configuration

Property Value
test_cases [{identifier: "AAPL", identifier_type: TICKER}]
test_search_query "Apple"

⚠️ Limitations

  • Rate limits: Yahoo Finance may throttle requests. No built-in rate limiter — rely on core sync Semaphore.
  • ISIN resolution: Not all ISINs are resolvable by yfinance (depends on market coverage).
  • Data gaps: Some tickers may have missing days or delayed data.

📦 Dependency

  • Library: yfinance — installed via pipenv install yfinance.
  • Optional import: If yfinance is not installed, current/history/search calls raise an AssetSourceError with error code NOT_AVAILABLE; metadata refresh degrades to None.
  • Transitive: pandas (required by yfinance).