Real Time Market Data: Sources, Delays and Costs

Real-Time, Delayed and Historical Data

What real time market data really means, how it differs from delayed and snapshot data, where it comes from, what it costs and how to judge its quality.

Intermediate3 min readUpdated 3 Oct 2026

Lesson 15 of 27

Real time market data shows prices as trades and quotes happen, rather than minutes later. It sounds simple, but "real time" covers a wide range: a professional direct feed from an exchange arrives within microseconds, while a free web chart may refresh once a second from a consolidated source. For a long term investor, a short delay hardly matters. For a day trader or a bot reacting to price moves, data quality and speed directly affect results. Understanding where your data comes from helps you know what you can and cannot rely on.

Types of market data delivery#

Type	Description	Typical users
Delayed	Prices shown with a delay, often 15 minutes for exchange data	Casual investors, free sites
Snapshot	Current price on request, not streamed	Occasional checks
Real time streaming	Continuous updates as they happen	Active traders, bots
Direct exchange feeds	Raw feeds straight from the venue	Professional and high frequency firms
Consolidated feeds	Combined data from many venues	Brokers, retail platforms

Consolidated versus direct feeds#

In US stocks, trading happens on many exchanges. The Securities Information Processors (SIPs) combine their quotes and trades into a consolidated tape. Direct feeds from each exchange are faster because they skip the consolidation step, and professional firms often build their own view of the market from them. Retail platforms usually show consolidated or broker processed data. See Exchanges and Latency in Trading.

Crypto data#

Each crypto exchange has its own order book and price, so "the price of Bitcoin" depends on the venue. Exchanges stream data free through WebSocket APIs. Index prices, such as those used for perpetual futures or settlement, are calculated from several exchanges. See Mark Price vs Index Price and WebSocket Market Data Streams.

On TradeLabs AI, the live charts use streaming exchange data. For Polymarket's crypto up or down rounds, it matters which source settles the market, because a different exchange's price can differ slightly at the deciding moment. See Price to Beat and How Rounds Settle.

What real time data costs#

Market	Typical cost model
US stocks	Exchange fees passed through brokers; non professional rates are much lower than professional
Futures	Exchange fees per exchange group, monthly
Forex	Usually broker quotes, no separate fee
Crypto	Usually free from exchanges

See Market Data Fees.

Judging data quality#

Question	Why it matters
Is it truly real time or delayed?	Delays hide the current market
Which venues are included?	One venue may not reflect the whole market
Are timestamps from the exchange or the receiver?	Determines how you measure delays
How are outages handled?	Silent gaps cause bad decisions. See Monitoring Positions, P&L and Risk
Does it include quotes or only trades?	Needed to model spreads

Practical tips#

Match data to strategy speed. Slow strategies do not need expensive feeds.
Use the same source live as in backtests, or measure differences between them.
Record your live data for later replay and debugging. See Market Data Replay.
Detect stale data and stop trading on it.

Frequently asked questions#

What is real time market data?#

Price and quote information delivered as trades and quote changes happen, rather than after a delay.

Why is stock data delayed on free sites?#

Exchanges charge for real time data, so free services often show delayed prices, commonly 15 minutes behind.

Is crypto market data free?#

Most crypto exchanges provide real time data free through their APIs, though professional data vendors charge for cleaned and combined datasets.

Next, learn how to move data reliably from source to storage in Data Pipelines and ETL.

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Next lessonData Pipelines and ETLHow trading data pipelines extract, transform and load market data reliably. Learn pipeline stages, scheduling, idempotent loads, validation checks and monitoring.