Market Data API

Overview

A market data API provides programmatic access to prices, quotes, trades, order books, volumes, instruments, and related financial market information. Data quality depends on source venues, aggregation, timestamps, symbol mapping, liquidity, and update frequency. Consumers use them for pricing, valuation, conversion estimates, analytics, risk controls, and trading interfaces. Missing, duplicated, stale, or corrected observations can materially affect decisions. A successful transport result from Market Data API should not be interpreted beyond the exact API state documented by the provider. The Market Data API owner should publish stable error semantics and guidance on whether correction, retry, status lookup, or escalation is appropriate.

Critical pricing should use outlier controls, fallback sources, and stale-data rejection. Market data APIs deliver real-time, delayed, or historical observations through request-response endpoints or streaming subscriptions. Logs should preserve which observation supported a financial decision without exposing proprietary feeds. A quoted price may be indicative rather than executable, especially for large or illiquid orders. Clients should verify instrument and currency units, source coverage, timestamp semantics, freshness, and licensing. Observability for Market Data API should record operation, version, principal, request ID, latency, retry count, error code, and final state without exposing secrets.

The Market Data API contract should define identifiers, validation, authorization, status semantics, errors, limits, and version behavior at the same boundary.

For Market Data API, the application should preserve a correlation path from request construction through response, asynchronous completion, and final business state.

Changes to Market Data API should be checked against older clients, stored payloads, enum growth, default behavior, and retry assumptions.