The non-Hermitian PT -symmetric quantum-mechanical Hamiltonian H = p 2 + x 2 (ix) ε has real, positive, and discrete eigenvalues for all ε ≥ 0. These eigenvalues are analytic continuations of the harmonic-oscillator eigenvalues E n = 2n + 1 (n = 0, 1, 2, 3, . . .) at ε = 0. However, the harmonic oscillator also has negative eigenvalues E n = −2n − 1 (n = 0, 1, 2, 3, . . .), and one may ask whether it is equally possible to continue analytically from these eigenvalues. It is shown in this paper that for appropriate PT -symmetric boundary conditions the Hamiltonian H = p 2 + x 2 (ix) ε also has real and negative discrete eigenvalues. The negative eigenvalues fall into classes labeled by the integer N (N = 1, 2, 3, . . .). For the N th class of eigenvalues, ε lies in the range (4N −6)/3 < ε < 4N −2. At the low and high ends of this range, the eigenvalues are all infinite. At the special intermediate value ε = 2N − 2 the eigenvalues are the negatives of those of the conventional Hermitian Hamiltonian H = p 2 + x 2N . However, when ε = 2N − 2, there are infinitely many complex eigenvalues. Thus, while the positive-spectrum sector of the Hamiltonian H = p 2 + x 2 (ix) ε has an unbroken PT symmetry (the eigenvalues are all real), the negative-spectrum sector of H = p 2 +x 2 (ix) ε has a broken PT symmetry (only some of the eigenvalues are real).