Bond fund giant Pacific Investment Management Co., or Pimco, cut its holdings of U.S. government-related holdings in its flagship bond fund in September for the third straight month. Steve Rodosky, head of Treasury and derivatives trading at Pimco, said earlier this month that “the best day in Treasurys is probably behind us.” He has sought better returns in high-quality investment-grade corporate bonds, mortgage-backed securities and municipal debt since July. The …