NOTE 9 — COMMON STOCK WARRANT LIABILITY

In connection with the Company’s emergence from Chapter 11 bankruptcy (the “Bankruptcy Proceedings”) on June 11, 2010 (the “Effective Date”), Signature issued warrants to purchase an aggregate of 1.5 million shares of the Company’s common stock (the “Warrants”). The aggregate purchase price for the Warrants was $0.3 million, due in equal installments as the Warrants vest. The Warrants vested 20% upon issuance and, thereafter, vest 20% annually on the anniversary of the issuance date. As of September 30, 2013, the Warrants are 80% vested and the Company has received $0.2 million of the aggregate purchase price. The Warrants expire in June 2020 and had an original exercise price of $10.30 per share, as adjusted to reflect the Reverse Split. The Warrants were issued without registration in reliance on the exemption set forth in Section 4(2) of the Securities Act of 1933, as amended.

The Warrants include customary terms that provide for certain adjustments of the exercise price and the number of shares of common stock to be issued upon the exercise of the Warrants in the event of stock splits, stock dividends, pro rata distributions and certain other fundamental transactions. Additionally, the Warrants are subject to pricing protection provisions and are eligible to receive rights to subscribe for the purchase of common stock under rights offering transactions. During the term of the Warrants, the pricing protection provisions provide that certain issuances of new shares of common stock at prices below the current exercise price of the Warrants automatically reduce the exercise price of the Warrants to the lowest per share purchase price of common stock issued.

In October 2010, January 2011, and April 2011, restricted common stock was issued to nonexecutive members of the board of directors (the “Board”) under the Company’s director compensation program (the “Director Compensation Program”) that each triggered the pricing protection provisions of the Warrants. The restricted common stock issued to nonexecutive members of the Board in April 2011 reduced the exercise price of the Warrants to $6.90 per share, as adjusted to reflect the Reverse Split. In July 2011, the Company issued approximately 0.3 million shares of common stock, as adjusted to reflect the Reverse Split, as purchase consideration in the NABCO business combination. The NABCO business combination common stock was issued at $6.64 per share, as adjusted to reflect the Reverse Split, thereby reducing the exercise price of the Warrants to $6.64 per share, as adjusted to reflect the Reverse Split; however, the holders of approximately 79.3% of the Warrants waived the pricing protection provisions related to shares issued in the NABCO business combination and the exercise price related to those Warrants remains at $6.90 per share, as adjusted to reflect the Reverse Split. See Note 17—Subsequent Events for additional information related to the Reverse Split.

The Company utilizes a trinomial lattice option pricing model to estimate the fair value of the common stock warrant liability. A decrease in the common stock warrant liability results in other income, while an increase in the common stock warrant liability results in other expense.

The following table presents changes in the fair value of the common stock warrant liability during the periods indicated:

	Three Months Ended September 30,					Nine Months Ended September 30,
(Dollars in thousands)	2013		2012			2013			2012
Beginning balance	$	7,500	$	2,000	$		2,350	$		1,403
Change in fair value of common stock warrant liability		3,300		850			8,450			1,447
Ending balance	$	10,800	$	2,850	$		10,800	$		2,850

The following table summarizes the assumptions used to estimate the fair value of the common stock warrant liability during the periods indicated, as if the Reverse Split occurred on December 31, 2011:

	Three Months Ended September 30,							Nine Months Ended September 30,
(Weighted averages)	2013			2012				2013				2012
Expected term (years)		4.1			7.2				5.3				7.6
Volatility		55.0	%		51.0	%			53.0	%			49.5	%
Risk-free rate		0.99	%		1.07	%			1.12	%			1.36	%
Exercise multiple		2.8			2.8				2.8				2.8
Market price of Signature common stock	$	12.00		$	4.60		$		8.90		$		3.60
Exercise price	$	6.85		$	6.85		$		6.85		$		6.85