Marketable Securities

6 Months Ended

Sep. 30, 2011

NOTE E — MARKETABLE SECURITIES

At September 30, 2011, available-for-sale securities consisted of the following:


	September 30, 2011
	(in millions)
	Aggregate		Gross		Gross
	Cost		Unrealized		Unrealized		Aggregate
	Basis		Gains		Losses		Fair Value
U.S. Treasury and agency securities	$	68	$	—	$	—	$	68
Municipal securities		1		—		—		1
Corporate debt securities		110		—		—		110

	$	179	$	—	$	—	$	179

At September 30, 2011, the Company did not have any debt securities that were in a continuous unrealized loss position for greater than 12 months. Proceeds from the sale of marketable securities and realized gains and realized losses were approximately $27 million and less than $1 million, respectively. At September 30, 2011, $89 million of marketable securities had scheduled maturities of less than one year, and approximately $90 million had maturities of greater than one year but not exceeding three years.

At March 31, 2011, available-for-sale securities consisted of the following:


	March 31, 2011
	(in millions)
	Aggregate		Gross		Gross
	Cost		Unrealized		Unrealized		Aggregate
	Basis		Gains		Losses		Fair Value
U.S. Treasury and agency securities	$	60	$	—	$	—	$	60
Municipal securities		2		—		—		2
Corporate debt securities		117		—		—		117

	$	179	$	—	$	—	$	179

At March 31, 2011, the Company did not have any debt securities that were in a continuous unrealized loss position for greater than 12 months. At March 31, 2011, $75 million of marketable securities had scheduled maturities of less than one year, and approximately $104 million had scheduled maturities of greater than one year but not exceeding three years.