Derivative Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2012

Schedule of changes in derivative financial instruments liability balance

Date	Description	Warrants		Derivative Instrument Liability (in thousands)
12/31/2010	Balance of derivative financial instruments liability	728,469		$	3,487
3/31/2011	Fair value of new warrants issued during the quarter	210,000		1,313
3/31/2011	Change in fair value of warrants during the quarter recognized as other expense in the statement of operations	—		339
3/31/2011	Balance of derivative financial instruments liability	938,469		5,139
6/30/2011	Fair value of new warrants issued during the quarter	611,207		2,608
6/30/2011	Exercise of warrants during the quarter	(80,000	)	(486		)
6/30/2011	Change in fair value of warrants during the quarter recognized as other expense in the statement of operations	—		698
6/30/2011	Balance of derivative financial instruments liability	1,469,676		7,959
9/30/2011	Fair value of new warrants issued during the quarter	40,458		285
9/30/2011	Change in fair value of warrants during the quarter recognized as other income in the statement of operations	—		(4,383		)
9/30/2011	Balance of derivative financial instruments liability	1,510,134		3,861
12/31/2011	Fair value of new warrants issued during the quarter	1,810,294		3,082
12/31/2011	Reclass of derivative liability to equity during the quarter	(1,055,268	)	(1,707		)
12/31/2011	Change in fair value of warrants during the quarter recognized as other income in the statement of operations	—		(1,911		)
12/31/2011	Balance of derivative financial instruments liability	2,265,160		3,325

3/31/2012	Fair value of new warrants issued during the quarter	—		—
3/31/2012	Change in fair value of warrants during the quarter	—		(8		)

3/31/2012	Balance of derivative financial instruments liability	2,265,160		3,317
6/30/2012	Warrants classified to derivative liability during quarter	112,500		169
6/30/2012	Change in fair value of warrants during the quarter	—		1,317
6/30/2012	Balance of derivative financial instruments liability	2,377,660		4,803
9/30/2012	Fair value of new warrants issued during the quarter	—		—
9/30/2012	Change in fair value of warrants during the quarter	—		(140		)

9/30/2012	Balance of derivative financial instruments liability	2,377,660		4,663
12/31/2012	Fair value of new warrants issued during the quarter	—		—
12/31/2012	Change in fair value of warrants during the quarter	—		764
12/31/2012	Reclass of derivative liability to equity during the quarter	(112,500	)	(169		)
12/31/2012	Balance of derivative financial instruments liability	2,265,160		$	5,258

(1) Number of warrants outstanding represented above reflect a retroactive effect of a one for two (1:2) reverse stock split effective on November 30, 2011.

Derivative instrument liability | Warrants | Black-Scholes option pricing model

Derivative Financial Instruments

Schedule of range of assumptions used to determine the fair value of the warrants

	Year ended December 31, 2012	Year ended December 31, 2011
Fair value of Synergy common stock	$4.05-$5.26	$3.50 - $9.04
Expected warrant term	5-7 years	4-7 years
Risk-free interest rate	0.23%-1.33%	0.36% - 2.22%
Expected volatility	60%	70%-90%
Dividend yield	0%	0%

Derivative instrument liability | Warrants | Binomial model

Derivative Financial Instruments

Schedule of range of assumptions used to determine the fair value of the warrants

	Year ended December 31,
	2012	2011
Estimated fair value of Synergy common stock	$3.28-$4.53	$2.71-$5.02	(*)
Expected warrant term	4.13-4.63 years	5-7 years
Risk-free interest rate	0.62%-1.04%	0.90%-2.64%
Expected volatility	60%	70%-90%
Dividend yield	0%	0%

(*) Restated for 1:2 reverse stock split effective November 30, 2011.