How to Calculate a Single Quarter's Results from Year-to-Date Figures
Subtract cumulative half-year and nine-month figures to calculate individual quarters. Learn why margins and EPS cannot simply be subtracted, and understand the limits of annualization.
Calculate the second quarter alone by subtracting first-quarter cumulative amounts from half-year cumulative amounts, and the third quarter alone by subtracting half-year amounts from nine-month amounts. The amounts must use the same reporting scope and accounting policies. Subtracting ratios or EPS as though they were additive amounts can produce a different result, so check their underlying numerators and denominators.
Check that the column is cumulative before subtracting
Quarterly income statements may show both three-month and cumulative columns. Subtracting the previous quarter from a figure already presented for three months creates an error. Cash flow statements, by contrast, often need to be read cumulatively, so check the period for each statement directly. The OpenDART developer guide also distinguishes current-period amounts from current-period cumulative amounts as separate fields. When transferring data, retain the report type, consolidated status, period, and cumulative status alongside the account name.
Recalculate margins from the amounts after subtraction
The difference between cumulative operating margins is not a single quarter's operating margin. Subtract revenue and operating profit separately, then divide the quarter's operating profit by its revenue. EPS can also use different weighted-average share counts for different periods, so simply subtracting cumulative EPS figures may differ from the correct quarterly EPS. Balance sheet assets and borrowings are point-in-time balances: the difference between two closing balances is only a net movement, rather than the quarter's assets or total new borrowing.
State the limits of fourth-quarter derivation and annualization
Subtracting nine-month cumulative amounts from annual amounts gives a fourth-quarter difference, but check whether it includes year-end audit adjustments or effects of restated comparatives. Do not casually subtract uncorrected nine-month figures from the latest annual figures. Multiplying a single quarter by 4 to annualize it is likewise an assumption that the current pace continues, rather than a forecast of future results. Strong seasonality or changes in acquisition scope require separate scenarios, and annualized amounts should not be presented as confirmed results.
Worked example
Hypothetical example: All amounts below are in units of KRW 100 million. First-quarter cumulative revenue of 100 and operating profit of 10, followed by half-year cumulative revenue of 250 and operating profit of 40, imply second-quarter-only revenue of 150 and operating profit of 30. The second-quarter operating margin is therefore 20%. Subtracting the first quarter's 10% margin from the half-year cumulative margin of 16% gives 6%, which is not the second-quarter margin. If nine-month cumulative revenue is 420, third-quarter-only revenue is 170; adding the cumulative amounts to arrive at 770 would be incorrect.
What to check
- Identify whether you are using the three-month or cumulative column.
- Align consolidation scope and correction status for the two amounts being subtracted.
- Recalculate single-quarter margins from revenue and profit amounts.
- Do not automatically apply cumulative subtraction to EPS, balances, or ratios.
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.