4. Investment in Available-for-Sale Securities

The following is a summary of the Company’s investment in available-for-sale securities as of June 30, 2011:

	Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. federal agency securities	$	50,405	$	795	$	-		$	51,200
Certificates of deposit		1,813,366		17,365		(9,790	)		1,820,941
Corporate securities		791,502		968		(15,087	)		777,383
	$	2,655,273	$	19,128	$	(24,877	)	$	2,649,524

The Company’s investment portfolio had a gross realized loss of $853 and $249 for the six months ended June 30, 2011 and 2010, respectively. The Company’s investment portfolio had a gross realized loss of $3,257 and $1,176 for the three months ended June 30, 2011 and 2010, respectively. The Company’s investment portfolio has fourteen positions with an unrealized loss as of June 30, 2011.

The cost and fair value of investment in available-for-sale debt securities, by contractual maturity, as of June 30, 2011, were as follows:

	Cost		Fair Value
Due within one year	$	999,026	$	993,485
Due after one year through three years		1,542,209		1,541,180
Due after three years		114,038		114,859
	$	2,655,273	$	2,649,524

Expected maturities will differ from contractual maturities because the issuers of certain debt securities have the right to call or prepay their obligations without any penalties. Accordingly, the Company has classified the entire fair value of its investment in available-for-sale debt securities as current assets in the accompanying balance sheets.