  We analyze the Coulomb branch of Matrix string theory in the presence of
NS5-branes. If we regard the components of U(1) gauge fields as the dualized
longitudinal coordinates, we obtain the symmetric product of AdS_3 x S^3 x R^4
as the geometry of Coulomb branch. We observe that the absence or presence of
the nonzero electric flux determines whether the string propagates in bulk as
an ordinary closed string or is forced to live near the boundary.
  We further discuss the issues of the physical spectrum from the viewpoint of
Matrix string theory. We show that the twisted sectors of CFT on the symmetric
orbifold, which correspond to glued strings, turn out to yield many chiral
primaries that were hitherto considered to be missing. We also comment on the
threshold energy in Liouville sector where continuous spectrum begins.
