Stock market data infrastructure
Understand financial reporting periods
Separate fiscal year labels, period-end dates, filing dates, balance-sheet instants, and cumulative versus standalone cash flows.
Documentation revised
Retain the period identity
FY, H1, H2, and Q1–Q4 describe reporting frequency; fiscal_year and period_end identify the issuer's fiscal period. Companies do not all end their fiscal year in December. A fiscal-year label must not be converted to a calendar-year end without checking the actual date.
Do not confuse availability with period end
A statement period can end well before it is filed. filed_date and filing metadata describe publication timing where available; updated_at describes a storage update. None of these alone creates a historical as-of dataset suitable for assuming what was publicly known on an earlier date.
Aggregate flows and instants differently
Income and cash-flow items describe activity over a period; assets and liabilities are balance-sheet instants. Quarterly SEC cash flow can be year-to-date cumulative. Inspect cash_flow_basis and use cash_flow=standalone when appropriate. TTM flows sum eligible quarters, while balance-sheet values use the latest instant; never sum four asset balances.