This excerpt taken from the XMSR 10-K filed Mar 4, 2005.
(f) 1.75% Convertible Subordinated Notes
In November 2004, the Company completed the sale of $300 million aggregate principal amount of its 1.75% Convertible Senior Notes due 2009. In January 2005, an over-allotment option was exercised and an additional $100 million aggregate principal amount of notes were issued. The notes may be converted by the holder, at its option, into shares of the Companys Class A common stock initially at a conversion rate of 20.0 shares of Class A common stock per $1,000 principal amount, which is equivalent to an initial conversion price of $50.00 per share of Class A common stock (subject to adjustment in certain events), at any time until December 1, 2009. The notes are not redeemable at the Companys option prior to the stated maturity.