Supplemental Executive Retirement Plan

9 Months Ended

Sep. 30, 2012

Supplemental Executive Retirement Plan

Supplemental Executive Retirement Plan

7. Supplemental Executive Retirement Plan

We maintain the United Therapeutics Corporation Supplemental Executive Retirement Plan (SERP) to provide retirement benefits to certain senior members of our management team. To help fund our expected obligations under the SERP, we maintain the United Therapeutics Corporation Supplemental Executive Retirement Plan Rabbi Trust Document (Rabbi Trust). The balance in the Rabbi Trust was approximately $5.1 million as of September 30, 2012 and December 31, 2011. The Rabbi Trust is irrevocable and SERP participants have no preferred claim on, nor any beneficial ownership interest in, any assets of the Rabbi Trust. The investments in the Rabbi Trust are classified as restricted marketable investments and cash on our consolidated balance sheets.

Net periodic pension cost consists of the following (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2012		2011		2012		2011
Service cost	$	1,078	$	1,079	$	3,236	$	3,176
Interest cost	369		352		1,106		1,004
Amortization of prior service costs	207		207		620		566
Amortization of net actuarial loss	—		20		—		71
Net pension expense	$	1,654	$	1,658	$	4,962	$	4,817