  We consider a two-dimensional Fermi liquid in the vicinity of a
spin-density-wave transition to a phase with commensurate antiferromagnetic
long-range order. We assume that near the transition, the Fermi surface is
large and crosses the magnetic Brillouin zone boundary. We show that under
these conditions, the self-energy corrections to the dynamical spin
susceptibility, $\chi (q, \omega)$, and to the quasiparticle spectral function
function, $A(k, \omega)$, are divergent near the transition. We identify and
sum the series of most singular diagrams, and obtain a solution for $\chi(q,
\omega)$ and an approximate solution for $A(k, \omega)$. We show that (i)
$A(k)$ at a given, small $\omega$ has an extra peak at $k = k_F + \pi$ (`shadow
band'), and (ii) the dispersion near the crossing points is much flatter than
for free electrons. The relevance of these results to recent photoemission
experiments in $YBCO$ and $Bi2212$ systems is discussed.
