Ositrustees Market Data Accuracy: Timestamps, Sessions and Source Context

Ositrustees Market Data Accuracy: Timestamps, Sessions and Source Context
Market-data discrepancies are often caused by configuration differences before they are caused by incorrect data.
At Ositrustees, we approach market-data comparison as a structured research problem: first align the inputs, then compare the outputs.
That means looking at instrument identity, timestamps, trading sessions, chart intervals, historical adjustments and source context before deciding that two market-data views actually conflict.

1. Start with the exact instrument A company name alone is not enough to identify a market instrument. The same company may trade on multiple exchanges, and similar ticker symbols can refer to different securities in different markets. Before comparing values, confirm:
2. ticker
3. exchange
4. currency
5. market This sounds basic, but instrument mismatches can make two otherwise valid datasets look inconsistent.
6. Align timestamps and time zones A timestamp only makes sense in context. For example, a value recorded at 10:00 ET is not directly comparable with a value shown at 10:00 UTC. When comparing market-data feeds, check:
7. the recorded timestamp
8. the time zone
9. whether the timestamp refers to trade time, quote time or interface refresh time A screen refresh and a market-data update are not necessarily the same event.
10. Check the trading session Regular-session and extended-hours data can produce different:
11. opening prices
12. highs and lows
13. volume totals
14. chart shapes Two platforms can therefore display different-looking charts while both are technically correct. Before treating the difference as a problem, confirm which trading session each view includes.
15. Compare chart intervals Chart intervals change how raw market activity is aggregated. A one-minute chart and a five-minute chart are not showing the same level of detail, even if they cover the same period. This matters when comparing:
16. price bars
17. volume
18. short-term volatility
19. intraday highs and lows The interval should be aligned before differences are interpreted.
20. Review historical adjustments Historical datasets may be adjusted for corporate actions such as stock splits. Different adjustment methodologies can change how historical price series appear. That means two valid sources may show different historical values while still describing the same underlying instrument. For research purposes, the key question is not simply: Which chart is right?

A better question is:
Are both charts using the same adjustment method?

1. Add source context Source context matters just as much as chart configuration. A market-data feed, company publication, technical article, user review and search summary are different types of sources. They should not automatically be treated as equivalent. Repeated coverage also does not necessarily mean independent confirmation. One original statement may be quoted or summarized across several pages. For that reason, Ositrustees treats source context as part of the research workflow rather than as an afterthought.
2. Separate observation from interpretation A useful research note distinguishes between what the data directly shows and what the researcher thinks it means. For example: Observation: several instruments in the same sector moved during the same period. Interpretation: sector activity caused the move in a specific instrument. The first statement is observable from the data. The second needs additional evidence. Keeping those two layers separate makes research easier to review later. A practical comparison workflow A simple market-data comparison process can be summarized as: Identify → Align → Compare → Interpret Identify Confirm the instrument, exchange and market. Align Match timestamps, sessions, intervals and adjustment methods. Compare Review the actual differences between data views. Interpret Only then decide whether the discrepancy is meaningful. This is the same principle behind the Ositrustees financial data and analytical technology workflow: reduce ambiguity in the inputs before drawing conclusions from the output. Further reading Ositrustees recently published related work around market-data accuracy and source verification. Yahoo Finance coverage: https://finance.yahoo.com/markets/articles/ositrustees-introduces-2026-framework-strengthen-204200095.html Ositrustees Research Notes Research. Compare. Verify.

Comments

[Arhan Canli]

Adjustment is where I've seen the "which chart is right" question go wrong most, and it's more than splits. A split-adjusted series and a split-plus-dividend ("total return") adjusted series have the same dates and different closes, and the gap grows the further back you look: yfinance's default auto_adjust=True hands you the second kind, many chart tools show the first. Two views can both be correct and still differ by several percent on a 2015 bar for a dividend payer.

A related trap on the timestamp side: SEC filings carry a filing date and an acceptance time, and in the EDGAR files I compared the acceptance time is shifted by an Eastern offset in some companies' files and not in others (450 filings measured, same filing differing between two files), so even "recorded timestamp" needs a "which file" label.

When you compare two views, do you record the adjustment mode next to the timestamp zone, or infer it from the numbers?

[Tedor Ositrustees]

Good point - we’d record the adjustment mode explicitly rather than infer it from the numbers.

For a reproducible comparison, the note should ideally include the timestamp/time zone and the series treatment: raw, split-adjusted, dividend-adjusted/total-return, or whatever methodology the source documents.

The same applies to filings: the source file and timestamp convention matter as much as the timestamp itself. Two values can be internally consistent and still not be directly comparable if those settings differ.

That’s exactly why we separate the observation from the explanation first.