  We study dynanics of $SU(N-4)$ gauge theories with fermions in rank-2
symmetric tensor and $N$ anti-fundamental representations, by perturbing
supersymmetric theories with anomaly-mediated supersymmetry breaking. We find
the $SU(N)\times U(1)$ global symmetry is dynamically broken to $SO(N)$ for
$N\geq 17$, a different result from conjectures in the literature. For $N<17$,
theories flow to infrared fixed points.
