IEX vs. SIP Market Data
IEX is a single exchange feed; SIP data consolidates eligible U.S. exchange reports through the consolidated tapes.
Read the draftReal-Time Market Data
What Does Real-Time Market Data Mean?
Real-time means a provider delivers eligible events soon after it receives them on a specified feed. It does not mean every U.S. venue is represented or that every screen updates at the same instant.
Draft updated · owner review pending
A feed has a coverage boundary
Alpaca documents an IEX stream, a SIP stream, and delayed SIP access. IEX is a single exchange; SIP consolidates eligible U.S. reports. A live IEX value can be fresh for IEX yet differ from a consolidated quote or from a broker using another source.
Delivery and display introduce timing
Provider processing, network delay, client calculation, UI refresh, and a user's system clock can all affect the time shown on screen. A changing market can outrun a snapshot. Check the event timestamp and feed before calling one value stale or incorrect.
Know the entitlement
An account's plan can govern which stream and recent historical data are available. Market Watch 360 uses the customer's own Alpaca connection in the desktop app; its website does not stream stock data or receive API credentials.
Sources and further reading
- Alpaca Market Data FAQFeed coverage, entitlements, and recent historical data
- Alpaca Real-time Stock DataStock stream messages, feed types, and delayed SIP