let c be a smooth, absolutely irreducible genus-3 curve over a number field m. suppose that the jacobian of c has complex multiplication by a sextic cm-field k. suppose further that k contains no imaginary quadratic subfield. we give a bound on the primes p of m such that the stable reduction of c at p contains three irreducible components of genus 1. joint work with bouw, cooley, lauter, manes, newton, ozman.