How to Distinguish Stock Data Update Times from Reference Dates
Learn to separate a screen’s refresh time from the reference dates for prices, financials, and estimates. Record timing for comparisons and reconstruct the information behind past decisions.
When checking stock information, record the access time, original release time, and period covered by the figure separately. Refreshing a screen does not bring all its information to the same point in time. Prices, financial statements, and earnings estimates each operate on different time bases.
Several kinds of time coexist on one screen
A share price is a value at a specific trading time, while financial statements cover an accounting period. Consensus depends on the forecasts included and the aggregation criteria. Seeing all three on a screen opened today does not mean they are all facts newly produced today. Naver Securities warns that supplied information may be delayed or contain errors, and Company Guide explains the data bases for its metrics. Rather than relying on one date at the top of the screen, check the actual basis for each item you plan to use. If that basis cannot be found, it is more accurate to avoid calling it real-time.
Fix the comparison time first
Comparing prices across sites requires matching not only the security, market, and currency but also the trading time. Do not compare one site’s closing price with another’s intraday value and conclude that one is wrong. When analyzing earnings estimate changes, also save the date on which each value was observed to enable later comparisons. New information may revise figures for historical periods, so keep both the reference period and retrieval date. A displayed time does not establish identical conventions either: for overseas data, check whether it is local or Korean time and where the date rolls over.
Preserve information available at the time for historical analysis
Reconstructing past investment decisions with today’s latest data can introduce results or amendments that had not been released then. Save the observation date and original publication time together in your analysis records, retaining later updates as new versions. When an estimate becomes an actual result, the nature of the information changes as well as its value. To compare a past forecast with a later outcome, preserve the record made at the forecast stage. You need not collect every screen, but retain the key figures, definitions, and sources used in a decision so another person can verify them.
Worked example
Hypothetical example: Suppose estimated operating profit of 100 was recorded in the morning, and actual operating profit of 90 appeared after an afternoon earnings release on the same day, both in units of KRW 100 million. The difference is 10 in those units, but recording this merely as a downward update to the same data erases the distinction between forecast and outcome. Label the first as a prerelease forecast and the second as the announced result, preserving their aggregation times as well. This makes the difference from expectations explainable.
What to check
- Have you separated access time from the original release time?
- Have you checked the respective bases for prices, actual results, and estimates?
- Have you aligned overseas time zones and trading-day boundaries?
- Have you avoided overwriting historical forecasts with actual results?
Sources and primary materials
This is educational material about research methods. For an actual company decision, verify the filings and primary sources for the relevant period.