Understanding the difference
It's common to observe slight differences between the closing prices provided at daily intervals (such as 1-day or 1-month) and intraday intervals (such as 1-minute to 8-hour intervals). This discrepancy typically occurs in volatile markets and affects highly traded instruments.
Example: Apple Inc. (AAPL)
Intraday Data Request (1-minute interval)
https://api.twelvedata.com/time_series?symbol=AAPL&interval=1min&date=2022-06-27&apikey=YOUR_API_KEY
Closing Price: 141.71001
Daily Data Request (1-day interval)
https://api.twelvedata.com/time_series?symbol=AAPL&interval=1day&date=2022-06-27&apikey=YOUR_API_KEY
Closing Price: 141.66000
The daily interval shows the official end-of-day (EOD) closing price, matching values published on financial websites and other financial services.
Why Does This Occur?
Intraday candles are built from real-time, tick-level data. At market close, the last recorded tick becomes the intraday closing price. However, exchanges can select a slightly different official closing price as their end-of-day value. These official values are usually released shortly after the market closes and are reflected in daily interval data. Intraday prices, however, remain unchanged once published, creating this minor discrepancy.
To summarise:
Intraday intervals: Reflect the last tick before market closure.
Daily intervals: Reflect the official, exchange-confirmed closing prices.