Maybe there's a tiny battery somewhere, just to make it realistic. The wire is also very thin, and thus needs little to no force to be bent. What happens to the wire? Does it twist on itself because each piece of the wire experiences a Lorentz force due to the magnetic field of the wire on the other side of the circuit? EDIT: Just did some sketching, it looks like the forces point inward indeed. So, I may have answered my own question :) EDIT 2: Correction, the forces point outward. That could mean it is self-stabilizing, since any part of the wire going outward (experiencing less magnetic field as a result) would require another one to go inward (experiencing more field).