Fitch Ratings has placed a BB final rating on Nomura Holdings' (TYO:8604) $1 billion perpetual subordinated debt securities, according to a Wednesday release.

The instruments are considered additional tier one securities, Fitch said.

The rating is four notches lower than the issuer's "bbb+" viability rating, consisting of two notches for loss severity and two notches for nonperformance risk.

Changes in the Japan-based financial group's viability rating could trigger similar actions on the securities, Fitch said.