A firm's capital structure includes the following securities. It has 500,000 shares of common stock (equity) outstanding, selling for $20 per share and is expected to pay a dividend of $1, and has an expected growth rate of 1%.The preferred stock share price is $50 and which a $2 dividend which is not expected to grow. The current price of the bonds is $818, and the coupon rate is 5%. The bonds will mature in 10 years.

question: What caused the price of this bond to drop from its initial price of $1,000 to its current price of $818?