Ron Logan, CFA, is a bond manager. He purchased $50 million in 6.0% coupon Southwest Manufacturing bonds at par three years ago. Today, the bonds are priced to yield 6.85%. The bondsmature in nine years. The Southwest bonds are trading at a: discount and the yield to maturity (YTM) has decreased since purchase premium, and the yield to maturity (YTM) has decreased since purchase discount, and the yield to maturity (YTM) has increased since purchase