  In recent numerical simulations of spherically symmetric gravitational
collapse a new type of critical behaviour, dominated by a sphaleron solution,
has been found. In contrast to the previously studied models, in this case
there is a finite gap in the spectrum of black-hole masses which is reminiscent
of a first order phase transition. We briefly summarize the essential features
of this phase transition and describe the basic heuristic picture underlying
the numerical phenomenology.
