  Motivated by the $\Sigma$-hypernuclear states reported in ($K^-,\pi^{\pm}$)
experiments, we have explored the possibility that there exists a
particle-stable $\Sigma^- nn$ bound state. For the J\"ulich \~A
hyperon-nucleon, realistic-force model, our calculations yield little reason to
expect a positive-parity bound state in either the $J = \frac{1}{2}$ or the $J
= \frac{3}{2}$ channels.
