Post-Close Reconciliation Window
A post-close reconciliation window is the short period after a market interval closes when OHLCV candles may still be checked, corrected, or updated before they are treated as final.
Market data does not always arrive in perfect order at the exact moment a time interval ends. An exchange may publish a trade a few milliseconds late, correct a previously reported transaction, or deliver messages after temporary network delays. Because OHLCV candles summarize all trading activity inside a fixed period, even a small late update can affect the open, high, low, close, or volume value. A post-close reconciliation window gives the data pipeline time to compare incoming messages against the candle that was just produced. The goal is to reduce the chance that a candle is marked final too early. For example, a one-minute candle may close at 12:01:00, but the provider may keep checking it briefly for data that belongs to the 12:00:00–12:00:59.999 interval. If a late trade belongs to that period, the candle can be revised before final publication. This does not mean the market is still open for that interval; it means the data summary is still being verified. The length of the reconciliation window depends on the exchange, asset, feed, latency, and provider policy. Clear handling of this window helps developers understand why recently closed candles may differ from historical candles retrieved later.
Why It Matters
A post-close reconciliation window helps prevent incomplete OHLCV candles from being treated as final too soon. It matters for trading systems, analytics tools, and backtests because small changes in recently closed candles can affect signals, charts, alerts, and historical calculations.
What is a post-close reconciliation window in crypto market data?
A post-close reconciliation window is the review period after a time interval ends but before its aggregated candle is considered stable. In crypto markets, this matters because trading runs continuously and messages can arrive from many venues at high speed. A data provider may need to process late trades, exchange corrections, or delayed sequence messages. The window acts as a buffer between interval close and final data confidence. It helps ensure that the candle reflects the activity that actually happened during the period. Without it, systems may store or act on candles that are still incomplete.
Why can an OHLCV candle change after the period closes?
An OHLCV candle can change after the period closes when new information arrives that belongs to the already closed interval. For example, a late trade could increase the high price, lower the low price, change the close, or add to total volume. Some exchanges also issue corrections or cancellations after the original event. If the data pipeline supports reconciliation, it can adjust the candle before treating it as final. This is especially important for short intervals such as one-second or one-minute candles. The closer a system is to real time, the more important it is to understand whether a candle is provisional or final.
How should developers handle post-close reconciliation windows?
Developers should treat recently closed candles as potentially changeable until the provider indicates they are final or enough time has passed according to the provider’s data policy. For dashboards, this may simply mean allowing the latest candle to update. For trading systems, it may mean avoiding final signal generation until the reconciliation window has passed. For backtesting, developers should use finalized historical data rather than snapshots captured too early. Systems can also store timestamps such as availability time or first published at to understand when each version became visible. Clear reconciliation handling improves consistency between live data, stored data, and later historical queries.
Real-World Example
A trading app displays a one-minute BTC/USD candle that closes at 10:30:00. Two seconds later, a delayed trade from 10:29:59 arrives and increases the candle’s volume and high price. During the post-close reconciliation window, the candle is updated so the final historical version matches what actually happened in that minute.
Post-Close Reconciliation Window and Market Data API
CoinAPI’s Market Data API helps teams work with real-time and historical crypto market data across exchanges. When building OHLCV charts, analytics, or trading workflows, understanding post-close reconciliation windows helps developers decide when a candle should be treated as provisional and when it is safe to rely on finalized historical data.