  Spectrum of elementary string states in type II string theory compactified on
a torus contains short multiplets which are invariant under only one quarter of
the space-time supersymmetry generators. $U$-duality transformation converts
these states into bound states of Dirichlet branes which wrap around
intersecting cycles of the internal torus. We study a class of these bound
states that are dual to the elementary string states at the first excited
level, and argue that the degeneracy of these bound states is in agreement with
the $U$-duality prediction.
