At a glance
- Keep index level, point change and percentage change in separate fields.
- Viewing time and the value's stated timestamp can differ.
- Pre-close and off-hour periods have specific trading meanings.
- Market data verify a market value; converted results require the external product's rules.
The red and green numbers on a market page do different jobs. One shows the index level; another shows how much it has moved. A service that takes some of those digits for a lottery result adds its own rules. Keeping these steps separate makes shared screenshots easier to understand.
Using SET’s explanations and market pages, we look at labels, units, timestamps and the difference between intraday and closing values. Our calculation examples are hypothetical, not current prices or lottery results. A service’s use of market data does not make the exchange its organiser.
Read the index name, units and time first, then check any separate rules used to convert the figure.
Index level and change are different fields
A market page may show the latest index, point change and percentage change. They are related but answer different questions. Read field names and units before copying.
SET's overview also displays market status and time. Keep these with the numbers rather than discarding the timestamp.
Index, Change and %Change may be translated or rearranged. Follow names and units on the original instead of a familiar left-to-right order. Retain headings in screenshots.
Intraday values need reference times
When two pages disagree, first check the times they reference. Values recorded at different moments are not the same snapshot.
A cropped image without index name and time can mislead. Keep index, date, time and market status together.
A third-party retrieval time is when its system fetched information, not necessarily when the market value occurred. If only retrieval time is given, acknowledge that limit instead of equating the timestamps.
External service rules require separate reading
Services referencing the same index may use different fields, times or holiday procedures. Obtain their conversion rules before expecting matching short results.
Reading an index correctly and verifying an external betting result are separate tasks. This article explains data rather than validates any provider's results or rules.
A clear rule identifies index, field, reference time and conversion. If those details are missing, only the underlying value may be verifiable. State that limit so official source names do not endorse unsupported conclusions.
Understand the index before extracting its ending
To understand a market snapshot, read the index's name and official definition. Decimal digits or endings alone do not explain what it represents.
Keeping the index name, units and time makes it easier to explain what the screenshot actually shows and what a later comment has added. You can then ask a specific question: is this the closing value for that date, or an intraday figure?
What SET Index represents
SET e-Learning describes a market-capitalisation-weighted index. Higher-weight securities influence it more than lower-weight ones. It is not a simple average of all prices or the baht price of one share.
SET and SET50 identify different aggregates. Separate them even when screenshots look alike; index names identify what is being measured.
Looking only at decimals removes much of the meaning. For market reading, retain level, movement and time. For a short-number conversion, record the procedure separately so questions for the market and converter remain distinct.
Practise points and percentages with invented figures
Suppose the reference level is 1,200.00 and the later value 1,212.00. The difference is +12.00 points, while 12/1,200 × 100 equals +1.00%. These invented figures do not describe SET on a particular date.
12.00 and 1.00 are related but belong to different fields. Extracting endings from point change and percentage change can yield different results even when both market values are correct.
Preserve signs: cropping +12.00 to 12.00 removes movement context. Store complete values and units before creating transformed fields, so source differences can be separated from truncation.
Trading and pre-close periods are distinct
SET's schedule separates pre-open, trading, pre-close and off-hour periods. Auction pricing has a specific role in pre-open and pre-close. An external 'close' label needs a status check rather than a remembered time.
The schedule also distinguishes security types. Do not apply one type's timing universally. We explain periods without setting an external lottery schedule; its chosen reference time needs its own rules.
To check a claimed close, retain index, business date, data timestamp and status, then consult market information. Posting after close does not make an earlier screenshot a closing value.
Holidays and reference dates can leave older values visible
Consult SET's holiday calendar when checking a trading day. A page displaying today's date can still show the previous business day's data.
Different source dates can explain disagreement without suggesting altered numbers. For overseas data, also identify the source's time zone.
Retain original time and zone alongside converted Thai time. Near midnight, dates can differ. We do not decide which date an external service should use; complete context lets its stated rule be checked.
Compare tables at each transformation step
If two short results claim the same index, first compare complete values at the same time, then the selected field, then treatment of decimals, signs and leading zeroes. This separates market errors from differing conversions.
If full values agree but conversion rules are absent, do not reverse-engineer an assumed rule from historical endings and attribute it to the organiser. Record agreement at the source and uncertainty at the next step.
A credible article needs more than a market image: data name, units, time, original link and a clear distinction between index explanation and converted results. Conversion claims need their own cited rule.
Check exactly what the publisher is reporting.
Preserve the date, round and source time zone.
Separate prize categories and retain every digit.
Compare sources and observations
Each source answers different questions. This table distinguishes comparable information from details that depend on the original context.
| Source or information | What it answers | What else to check | References |
|---|---|---|---|
| SET Index definition | Meaning and weighting principle | Not an external digit-conversion rule | References[1] |
| Index overview | Values, units, time and status | Preserve full values before abbreviation | References[2] |
| Trading schedule and Auction explanation | Trading periods and pre-close context | Applicable data type and current version | |
| Holiday calendar | Whether a market business day exists | The date actually attached to the source value | References[5] |
| External product's rules | Selection and conversion of market data | Rules must be disclosed before comparison |
Questions & answers
Further answers to questions that often arise when reading this topic
Are stock-index lottery references the same as investing?
An index describes market conditions. Using its digits in another service is a separate activity with separate rules.
An index or stock name in an image does not establish securities ownership or capital-market rights. Check what the service actually does.
How does an index level differ from its change?
The level is the index at a stated time; change compares it with a reference in points or percent.
Read the heading. In our invented example, +12 points equals +1% because percentage uses a base.
Are red and green colours sufficient?
Colours can signal movement without identifying index, units or time. Read the actual value and sign.
A monochrome image or different theme loses colour-only meaning. Keep field names and full values as text.
Can a pre-close image be called a closing result?
Why can today's page show yesterday's value?
It may retain the last business day's data. Check calendar, trading date and the timestamp attached to the value.
Today's date in a page header need not be the date of the market observation.
Can SET and SET50 be treated as one result?
Does SET endorse stock-index lottery products?
If full values match but short results differ, where is the error?
That remains uncertain until conversions are explained. Fields, times or decimal handling may differ.
Record full inputs and each stated rule. Do not infer a formula from endings and announce it as the organiser's method.
How should overseas times be recorded?
Keep the source time and time zone before adding a Thai conversion.
Dates can differ near midnight. Thai time alone can prevent direct comparison with an overseas announcement.
What makes a stock-index article informative?
Look for definitions, units, time, business date and original links, with converted information identified separately.
An ending without a named field is insufficient to verify the result or understand the market. Full context separates established claims from unanswered questions.
Sources and their scope
- SET e-Learning — SET Index definition ↗
Explains market-capitalisation weighting. Does not endorse stock-index lottery products or third-party digit extraction.
- Stock Exchange of Thailand — SET Index overview ↗
Names, units, timestamps and status provide market-data context. Values are not frozen or treated as lottery results.
- Stock Exchange of Thailand — Trading hours ↗
Pre-open, trading, pre-close and off-hour periods have security-specific conditions. Consult the current version.
- SET e-Learning — Opening price and closing price ↗
Explains Auction pricing in pre-open and pre-close, rather than conversion rules for external lottery results.
- Stock Exchange of Thailand — Holiday calendar ↗
The calendar page opened but its text did not return individual holiday entries. Provides a current checking channel without confirming a particular business day in this review.
Sources checked on 10 October 2026 · Original sources may change
