TEJ Quarterly Financial Data: 2010 Q1 to 2026 Q2

1. Objective
2. Load the data
3. Variables
4. Coverage
5. Sample observations
6. Missing values
7. Duplicate company-quarter observations
8. Example: TSMC (stock ID 2330)
9. Data limitations and interpretation
10. Conclusion

1. Objective

This report organizes quarterly financial information obtained from the Taiwan Economic Journal (TEJ) for the period 2010 Q1 to 2026 Q2. The requested measures are total equity (book value), market value of common stock, and quarterly net operating income. The measures are total monetary amounts, not per-share values. Original export units are retained.

2. Load the data

# Load the original TEJ data

financial_data <- read.csv(
  "TEJ_quarterly_2010Q1_2026Q2_4digit_stocks.csv",
  colClasses = c(stock_id = "character"),
  na.strings = c("", "NA"),
  stringsAsFactors = FALSE
)

# Check the data
dim(financial_data)

## [1] 131775     12

3. Variables

Field	Description
`stock_id`	Company/security identifier
`company_name`	Company name
`year_quarter`	Reporting quarter
`book_value_total_equity`	Total equity (book value)
`market_value_common_stock`	Market value of common stock
`operating_profit_quarter`	Estimated single-quarter operating income

4. Coverage

coverage <- data.frame(
  Measure = c("Observations", "Distinct stock IDs", "Distinct quarters", "First quarter", "Last quarter"),
  Value = c(
    nrow(financial_data),
    length(unique(financial_data$stock_id)),
    length(unique(financial_data$year_quarter)),
    min(financial_data$year_quarter),
    max(financial_data$year_quarter)
  )
)
knitr::kable(coverage)

Measure	Value
Observations	131775
Distinct stock IDs	2996
Distinct quarters	66
First quarter	2010Q1
Last quarter	2026Q2

5. Sample observations

To keep the published web page readable, only the first eight rows are displayed. The data file retains all observations.

knitr::kable(head(financial_data, 8))

stock_id	company_name	tej_co_id	quarter_end	year	quarter	year_quarter	book_value_total_equity	market_value_common_stock	operating_profit_quarter	operating_profit_ytd_original	profit_calculation_status
1101	TCC	1101 TCC	2010-03-31	2010	1	2010Q1	102157504	98600641	2152334	2152334	Q1_equals_YTD
1101	TCC	1101 TCC	2010-06-30	2010	2	2010Q2	102349225	89876378	3791319	5943653	difference_from_previous_YTD
1101	TCC	1101 TCC	2010-09-30	2010	3	2010Q3	109586305	109958645	4176068	10119721	difference_from_previous_YTD
1101	TCC	1101 TCC	2010-12-31	2010	4	2010Q4	124513778	121103340	5534591	15654312	difference_from_previous_YTD
1101	TCC	1101 TCC	2011-03-31	2011	1	2011Q1	128728151	131072213	3425462	3425462	Q1_equals_YTD
1101	TCC	1101 TCC	2011-06-30	2011	2	2011Q2	126201240	158025090	5605798	9031260	difference_from_previous_YTD
1101	TCC	1101 TCC	2011-09-30	2011	3	2011Q3	125190869	121472558	4357630	13388890	difference_from_previous_YTD
1101	TCC	1101 TCC	2011-12-31	2011	4	2011Q4	129320349	129226125	2783801	16172691	difference_from_previous_YTD

6. Missing values

missing_summary <- data.frame(
  Variable = names(financial_data),
  Missing_Count = colSums(is.na(financial_data)),
  Missing_Percent = round(colMeans(is.na(financial_data)) * 100, 2)
)
knitr::kable(missing_summary)

	Variable	Missing_Count	Missing_Percent
stock_id	stock_id	0	0.00
company_name	company_name	0	0.00
tej_co_id	tej_co_id	0	0.00
quarter_end	quarter_end	0	0.00
year	year	0	0.00
quarter	quarter	0	0.00
year_quarter	year_quarter	0	0.00
book_value_total_equity	book_value_total_equity	6	0.00
market_value_common_stock	market_value_common_stock	11791	8.95
operating_profit_quarter	operating_profit_quarter	18366	13.94
operating_profit_ytd_original	operating_profit_ytd_original	3198	2.43
profit_calculation_status	profit_calculation_status	0	0.00

Missing observations have been retained as NA; they have not been replaced with zeros.

7. Duplicate company-quarter observations

duplicate_count <- sum(duplicated(financial_data[c("stock_id", "year_quarter")]))
data.frame(Duplicate_Company_Quarter_Records = duplicate_count)

##   Duplicate_Company_Quarter_Records
## 1                                 0

8. Example: TSMC (stock ID 2330)

tsmc_2010 <- subset(
  financial_data,
  stock_id == "2330" & year_quarter %in% c("2010Q1", "2010Q2", "2010Q3", "2010Q4")
)
knitr::kable(tsmc_2010)

	stock_id	company_name	tej_co_id	quarter_end	year	quarter	year_quarter	book_value_total_equity	market_value_common_stock	operating_profit_quarter	operating_profit_ytd_original	profit_calculation_status
21640	2330	TSMC	2330 TSMC	2010-03-31	2010	1	2010Q1	532304702	1593081794	34127662	34127662	Q1_equals_YTD
21641	2330	TSMC	2330 TSMC	2010-06-30	2010	2	2010Q2	496872737	1569844030	40468693	74596355	difference_from_previous_YTD
21642	2330	TSMC	2330 TSMC	2010-09-30	2010	3	2010Q3	540904077	1606255266	43065502	117661857	difference_from_previous_YTD
21643	2330	TSMC	2330 TSMC	2010-12-31	2010	4	2010Q4	578704405	1839615538	41513478	159175335	difference_from_previous_YTD

9. Data limitations and interpretation

This is a processed TEJ export. The supplied source was filtered using four-digit stock IDs, not an independently verified TWSE-listing-status field. Consequently, the coverage of all TWSE-listed firms has not yet been confirmed; some TPEx or other four-digit identifiers may be included.
Quarterly operating profits were calculated from values believed to be year-to-date cumulative operating income. The quarterly calculation should be verified against the TEJ single-quarter series before treating it as confirmed.
Monetary figures retain the exported data’s scale. Verify the currency/unit setting in the original TEJ download before labeling numbers as dollars or thousands of dollars.
The reporting period is 2010 Q1 through 2026 Q2; not every security necessarily has observations for every quarter.

10. Conclusion

The report loads and summarizes the quarterly financial-data file, checks reporting-period coverage and missing values, and checks whether company-quarter records are duplicated. Full compliance with the assignment’s all listed firms requirement remains subject to verification using TEJ exchange-listing information.