Transactions (real flows): Monthly flow equals stock change minus reclassifications, exchange-rate moves and revaluations.
Notional-stock index: Build an index growing with flows divided by prior stocks, with December 2010 at 100.
Annual growth (YoY): YoY compares the index with the same month 12 months earlier, or cumulates monthly flows over a full year. Toy example: stocks 5400 to 5420 give 20, minus 5 plus 2 minus 1 leaves a flow of 16. The index rises from 130.00 to 130.385, and against 125.00 twelve months earlier gives 4.3% YoY.
Adjusted variant (headline): Add back net securitised transfers plus repayments, and strip notional cash-pool overdrafts. If banks sold 3 net off balance, adjusted flow is 16 plus 3 equals 19, indexed the same way.
Seasonal and calendar adjustment: Smooth seasonal and end-month calendar effects with X-12-ARIMA and X-13-ARIMA at euro-area level, with calendar and outlier cleaning then X-11 filtering. Factors are re-estimated yearly.
Enlargement linking: Chain-link new euro members with a factor so growth never jumps on entry.
Falling reported stocks do not mean firms got less credit. Securitisation moves loans off bank books while firm financing stays unchanged, so use adjusted data only. Notional cash-pool overdrafts are stripped as non-genuine financing. The series covers the euro area, not EU27, and excludes new lending, rates, standards, deposits, debt securities, non-bank loans and inter-company loans.