Kiwibank and its parent company New Zealand Post has had its outlook downgraded from stable to negative by international ratings agency Standard & Poor's.
Standard & Poor's credit analyst Adrian Chow said the negative outlook reflected a one in three chance that the rating on NZ Post could be lowered in the next two years due to rising economic risks in New Zealand which could affect the credit-standing of Kiwibank.
"Kiwibank represents about 70 per cent of the group's consolidated earnings and is a significant and growing contingent exposure to the group."
NZ Post guarantees Kiwibank's deposits and borrowings which were $12.3 billion and $1.5 billion respectively as of December 31, 2012.
Chow said the New Zealand government's provision of a $300 million uncalled capital facility would help NZ Post manage its contingent liabilities for Kiwibank.