Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 134	$ 142
Marketable securities	6,025	3,392
Prepaid expenses and other assets	135	330
Total current assets	6,294	3,864
Property and equipment, net	6	5
Patent portfolios and patent rights, net	4,951	9,799
Deposit	26	26
Total assets	11,277	13,694
Current liabilities
Accounts payable and accrued expenses	123	384
Accrued salaries and benefits	446	645
Warrant liabilities	702	2,959
Short-term deferred revenue	1,216	290
Short-term lease liabilities	183	178
Total current liabilities	2,670	4,456
Long-term deferred revenue	3,245	259
Long-term lease liabilities	44	229
Total liabilities	5,959	4,944
Stockholders' equity
Preferred stock
Common stock, $0.0001 par value, 100,000,000 shares authorized; 2,539,859 and 1,505,773 shares issued at December 31, 2015 and December 31, 2014, respectively; 2,539,847 and 1,505,761 shares outstanding at December 31, 2015 and December 31, 2014, respectively
Additional paid-in-capital	147,331	144,287
Treasury stock, at cost, 12 shares at December 31, 2016 and December 31, 2015	(264)	(264)
Accumulated deficit	(141,749)	(135,273)
Total stockholders' equity	5,318	8,750
Total liabilities and stockholders' equity	$ 11,277	$ 13,694

Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

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- Definition

Excess of issue price over par or stated value of the entity's capital stock and amounts received from other transactions involving the entity's stock or stockholders. Includes adjustments to additional paid in capital. Some examples of such adjustments include recording the issuance of debt with a beneficial conversion feature and certain tax consequences of equity instruments awarded to employees. Use this element for the aggregate amount of additional paid-in capital associated with common and preferred stock. For additional paid-in capital associated with only common stock, use the element additional paid in capital, common stock. For additional paid-in capital associated with only preferred stock, use the element additional paid in capital, preferred stock.