FDI stock is calculated differently depending on whether FDI goes to the subsidiaries of an enterprise or to its branches.
"For associate and subsidiary enterprises, […] the value of the share of their capital and reserves (including retained profits) attributable to the parent enterprise (this is equal to total assets minus total liabilities), plus the net indebtedness of the associate or subsidiary to the parent firm. For branches, […] the value of fixed assets and the value of current assets and investments, excluding amounts due from the parent, less liabilities to third parties."
(United nations Conference on Trade and Development (UNCTAD),
FDI Stock, visited 2010-01-21)