Equity Financings and Warrants	12 Months Ended
Dec. 31, 2013
Equity Financings and Warrants	(8) Equity Financings and Warrants 2012 Equity Financings Registered Direct Offering On August 2, 2012, the Company entered into subscription agreements with certain institutional investors (the “Investors”) in connection with its Registered Direct public offering (the “2012 Offering”), pursuant to which the Company sold an aggregate of 406,099 shares of its common stock and warrants to purchase up to 304,575 additional shares of its common stock to the Investors for aggregate gross proceeds of approximately $953,000, before deducting placement agent fees and other estimated offering expenses payable by the Company. The net proceeds to the Company were approximately $741,000, and the 2012 Offering closed on August 8, 2012. The common stock and warrants were sold in units consisting of one share of common stock and a warrant to purchase 0.75 shares of common stock. The purchase price for each unit was $2.35. Subject to certain ownership limitations, the warrants became exercisable six months after the issuance date, expire six years from their initial exercise date, and have an exercise price of $2.76 per share, equal to the closing bid price of ARCA’s common stock on the Nasdaq Capital Market on August 2, 2012. The 2012 Offering was effected as a takedown off the Company’s S-3 Registration Statement, which became effective on April 4, 2011, pursuant to a prospectus supplement filed with the Securities and Exchange Commission on August 3, 2012. The warrant agreements provide for settlement of the warrants in unregistered shares should an effective registration statement or current prospectus not be in place at the time a warrant is exercised. Private Investment in Public Equity (PIPE) Transactions On October 22, 2012, the Company entered into a Subscription Agreement (the “October 2012 Purchase Agreements”) with various accredited investors in connection with a private placement of its common stock and warrants. Certain Directors, Officers and Affiliates of ARCA were investors in the private placement. Pursuant to the October 2012 Purchase Agreement, the Company sold an aggregate of 137,530 shares of its common stock and warrants to purchase up to 103,148 additional shares of its common stock for aggregate gross proceeds of approximately $325,000, before deducting estimated offering expenses payable by the Company. The net proceeds to the Company were approximately $280,000, and the private placement closed on October 25, 2012. The common stock and warrants were sold in units consisting of one share of common stock and a warrant to purchase 0.75 shares of common stock. The purchase price for each unit was $2.36. The warrants were exercisable upon issuance, expire five years from the closing date, and have an exercise price of $1.80 per share, equal to 100% of the closing bid price of ARCA’s common stock on the NASDAQ Capital Market on October 22, 2012. On December 18, 2012, the Company entered into a Subscription Agreement (the “December 2012 Purchase Agreement”) with its Chief Executive Officer in connection with a private placement of ARCA’s common stock and warrants. Pursuant to the December 2012 Purchase Agreement, the Company sold an aggregate of 86,186 shares of its common stock and warrants to purchase up to 64,640 additional shares of its common stock for aggregate gross proceeds of approximately $250,000, before deducting estimated offering expenses payable by the Company. The net proceeds to the Company were approximately $230,000, and the private placement closed on December 20, 2012. The common stock and warrants were sold in units consisting of one share of common stock and a warrant to purchase 0.75 shares of common stock. The purchase price for each unit was $2.90. The warrants were exercisable upon issuance, expire five years from the closing date, and have an exercise price of $2.34 per share, equal to 100% of the closing bid price of ARCA’s common stock on the Nasdaq Capital Market on December 18, 2012. The Company filed a registration statement for the resale of the shares underlying the units sold in these private placements. The registration statement was declared effective by the Securities and Exchange Commission on February 14, 2013. 2013 Equity Financings Private Investment in Public Equity (PIPE) Transactions On January 22, 2013, the Company entered into a Subscription Agreement (the “January 2013 Purchase Agreement”) with various accredited investors and its Chief Executive Officer in connection with a private placement of its common stock and warrants. Pursuant to the January 2013 Purchase Agreement, the Company sold an aggregate of 356,430 shares of its common stock and warrants to purchase up to 249,501 additional shares of its common stock for aggregate gross proceeds of approximately $1 million, before deducting estimated offering expenses payable by the Company. The net proceeds to the Company were approximately $805,000, and the private placement closed on January 25, 2013. The common stock and warrants were sold in units consisting of one share of common stock and a warrant to purchase 0.70 shares of common stock. The purchase price for each unit was $2.81. The warrants were exercisable upon issuance, expire seven years from the date of issuance, and have an exercise price of $2.28 per share, equal to 100% of the closing bid price of ARCA’s common stock on the Nasdaq Capital Market on January 22, 2013. The Company filed a registration statement for the resale of the shares underlying the units sold in these private placements. The registration statement was declared effective by the Securities and Exchange Commission on February 14, 2013. In connection with this transaction, the Company agreed that, subject to certain exceptions, it would not, while the warrants are outstanding, effect or enter into an agreement to effect any issuance of common stock or securities convertible into, exercisable for or exchangeable for common stock in a “variable rate transaction,” which means a transaction in which the Company issues or sells any convertible securities either (A) at a conversion price, exercise price or exchange rate or other price that is based upon and/or varies with the trading prices of, or quotations for, the shares of common stock at any time after the initial issuance of such convertible securities, or (B) with a conversion, exercise or exchange price that is subject to being reset at some future date after the initial issuance of the convertible securities or upon the occurrence of the specified or contingent events directly or indirectly related to our business or the market for our common stock. In addition, the Company agreed that, subject to certain exceptions, if it issues securities within one year following the closing of the offering, each investor would have the right to purchase its pro rata share of a specified portion of the securities in the future offering on the same terms, conditions and price provided for in the proposed issuance of securities. Registered Direct Offering On January 31, 2013, the Company entered into a subscription agreement with certain institutional investors (the “Investors”) in connection with its Registered Direct public offering, pursuant to which the Company sold an aggregate of 164,636 shares of its common stock and warrants to purchase up to 65,855 additional shares of its common stock to the Investors for aggregate gross proceeds of approximately $730,000, before deducting placement agent fee and other estimated offering expenses payable by the Company. The net proceeds to the Company were approximately $616,000, and the offering closed on February 4, 2013. The common stock and warrants were sold in units consisting of one share of common stock and a warrant to purchase 0.40 shares of common stock. The purchase price for each unit was $4.43. The warrants were exercisable upon issuance, expire five years from the date of issuance, and have an exercise price of $4.13 per share, equal to the closing bid price of ARCA’s common stock on the Nasdaq Capital Market on January 31, 2013. The offering was effected as a takedown off the Company’s Registration Statement on Form S-3, as amended, which became effective on April 4, 2011, pursuant to a prospectus supplement filed with the Securities and Exchange Commission on February 1, 2013. The warrants provide for cashless exercise and settlement in unregistered shares if there is no effective registration statement registering, or the prospectus contained therein is not available for, the issuance of the shares of common stock underlying the warrants at the time of exercise. Public Offering On June 4, 2013, the Company sold shares of its Series A Convertible Preferred Stock (Preferred Stock) and warrants to purchase common stock in a public offering for aggregate gross proceeds of $20.0 million. The Company issued 125,000 shares of Preferred Stock and warrants to purchase up to 6,250,000 shares of common stock at a purchase price of $160 per share of Preferred Stock. The net proceeds, after deducting placement agent fees and other offering expenses payable by the Company, were approximately $17.9 million. ARCA’s Director and Chief Executive Officer participated in the offering, purchasing 781 shares of Preferred Stock and warrants to purchase 39,050 shares of common stock. Each share of Preferred Stock was initially convertible into 100 shares of the Company’s common stock at any time at the option of the holder. Each share of Preferred Stock had a liquidation preference of $.001 per share. The shares of Preferred Stock had no preferential dividends or redemption rights, and no voting rights except as required by law. As of December 31, 2013, 125,000 shares of the Preferred Stock had been converted into 12,500,000 shares of ARCA common stock. Each purchaser in the offering was issued a warrant to purchase 50 shares of the Company’s common stock for each share of Preferred Stock purchased. The warrants have an exercise price of $1.60 per share, will expire on the five year anniversary of the date of issuance, and were exercisable immediately upon issuance, provided that the holder will be prohibited from exercising the warrants if, as a result of such exercise, the holder, together with its affiliates, would beneficially own more than 9.99% of the total number of shares of common stock then issued and outstanding. The securities were sold pursuant to a placement agreement and have been registered under the Securities Act of 1933 pursuant to the Company’s Registration Statement on Form S-1, as amended (No.333-187508), which was declared effective by the Securities and Exchange Commission on May 29, 2013, and the Preferred Stock and Warrants were offered and sold pursuant to a prospectus dated May 30, 2013. In connection with the Preferred Stock financing, the Company recorded a non-cash dividend of approximately $2.0 million to recognize the intrinsic value of the embedded beneficial conversion feature. Typically, such a deemed dividend would be represented as a reduction in a company’s retained earnings and an increase in additional paid in capital in recognition of the reapportionment of common shareholder value to the preferred stock purchasers. However, since ARCA has an accumulated deficit, the deemed dividend is recognized by a reapportionment of additional paid in capital from common shareholders to additional paid in capital of preferred stock purchasers, which are combined in the Company’s statement of stockholders’ equity. 2014 Equity Financing Subsequent to December 31, 2013, the Company completed the following equity financing transaction: Registered Direct Offering On February 3, 2014, the Company agreed to sell to certain investors an aggregate of 5,116,228 shares of the Company’s common stock and warrants to purchase an aggregate of 1,279,057 shares of the Company’s common stock at a purchase price of $1.70 per share of Common Stock, for aggregate gross proceeds of approximately $8.7 million, before deducting placement agent fees and other offering related expenses. The offering closed on February 7, 2014, and the net proceeds to the Company were approximately $7.9 million. The common stock and warrants were sold in combination consisting of one share of common stock and a warrant to purchase 0.25 shares of common stock.. The warrants were exercisable upon issuance, expire five years from the date of issuance, and have an exercise price of $2.125 per share, equal to 125% of the closing bid price of ARCA’s common stock on the Nasdaq Capital Market on February 3, 2014. The offering was effected as a takedown off the Company’s Registration Statement on Form S-3, as amended, which became effective on April 4, 2011, pursuant to a prospectus supplement filed with the Securities and Exchange Commission on February 4, 2014. The warrants provide for cashless exercise and settlement in unregistered shares if there is no effective registration statement registering, or the prospectus contained therein is not available for, the issuance of the shares of common stock underlying the warrants at the time of exercise. Warrants As of December 31, 2013, warrants to purchase 8,147,484 shares of common stock were outstanding at exercise prices ranging from $1.60 to $116.89, with a weighted average exercise price per share of $2.32. These warrants, which were granted as part of various financing and business agreements, expire at various times between October 2016 and January 2020. Warrants were recorded in additional paid-in capital at their estimated fair market value at the date of grant using the Black-Scholes option-pricing model.

(8) Equity Financings and Warrants

2012 Equity Financings

Registered Direct Offering

On August 2, 2012, the Company entered into subscription agreements with certain institutional investors (the “Investors”) in connection with its Registered Direct public offering (the “2012 Offering”), pursuant to which the Company sold an aggregate of 406,099 shares of its common stock and warrants to purchase up to 304,575 additional shares of its common stock to the Investors for aggregate gross proceeds of approximately $953,000, before deducting placement agent fees and other estimated offering expenses payable by the Company. The net proceeds to the Company were approximately $741,000, and the 2012 Offering closed on August 8, 2012.

The common stock and warrants were sold in units consisting of one share of common stock and a warrant to purchase 0.75 shares of common stock. The purchase price for each unit was $2.35. Subject to certain ownership limitations, the warrants became exercisable six months after the issuance date, expire six years from their initial exercise date, and have an exercise price of $2.76 per share, equal to the closing bid price of ARCA’s common stock on the Nasdaq Capital Market on August 2, 2012. The 2012 Offering was effected as a takedown off the Company’s S-3 Registration Statement, which became effective on April 4, 2011, pursuant to a prospectus supplement filed with the Securities and Exchange Commission on August 3, 2012. The warrant agreements provide for settlement of the warrants in unregistered shares should an effective registration statement or current prospectus not be in place at the time a warrant is exercised.

Private Investment in Public Equity (PIPE) Transactions

On October 22, 2012, the Company entered into a Subscription Agreement (the “October 2012 Purchase Agreements”) with various accredited investors in connection with a private placement of its common stock and warrants. Certain Directors, Officers and Affiliates of ARCA were investors in the private placement. Pursuant to the October 2012 Purchase Agreement, the Company sold an aggregate of 137,530 shares of its common stock and warrants to purchase up to 103,148 additional shares of its common stock for aggregate gross proceeds of approximately $325,000, before deducting estimated offering expenses payable by the Company. The net proceeds to the Company were approximately $280,000, and the private placement closed on October 25, 2012.

The common stock and warrants were sold in units consisting of one share of common stock and a warrant to purchase 0.75 shares of common stock. The purchase price for each unit was $2.36. The warrants were exercisable upon issuance, expire five years from the closing date, and have an exercise price of $1.80 per share, equal to 100% of the closing bid price of ARCA’s common stock on the NASDAQ Capital Market on October 22, 2012.

On December 18, 2012, the Company entered into a Subscription Agreement (the “December 2012 Purchase Agreement”) with its Chief Executive Officer in connection with a private placement of ARCA’s common stock and warrants. Pursuant to the December 2012 Purchase Agreement, the Company sold an aggregate of 86,186 shares of its common stock and warrants to purchase up to 64,640 additional shares of its common stock for aggregate gross proceeds of approximately $250,000, before deducting estimated offering expenses payable by the Company. The net proceeds to the Company were approximately $230,000, and the private placement closed on December 20, 2012.

The common stock and warrants were sold in units consisting of one share of common stock and a warrant to purchase 0.75 shares of common stock. The purchase price for each unit was $2.90. The warrants were exercisable upon issuance, expire five years from the closing date, and have an exercise price of $2.34 per share, equal to 100% of the closing bid price of ARCA’s common stock on the Nasdaq Capital Market on December 18, 2012.

The Company filed a registration statement for the resale of the shares underlying the units sold in these private placements. The registration statement was declared effective by the Securities and Exchange Commission on February 14, 2013.

2013 Equity Financings

Private Investment in Public Equity (PIPE) Transactions

On January 22, 2013, the Company entered into a Subscription Agreement (the “January 2013 Purchase Agreement”) with various accredited investors and its Chief Executive Officer in connection with a private placement of its common stock and warrants. Pursuant to the January 2013 Purchase Agreement, the Company sold an aggregate of 356,430 shares of its common stock and warrants to purchase up to 249,501 additional shares of its common stock for aggregate gross proceeds of approximately $1 million, before deducting estimated offering expenses payable by the Company. The net proceeds to the Company were approximately $805,000, and the private placement closed on January 25, 2013.

The common stock and warrants were sold in units consisting of one share of common stock and a warrant to purchase 0.70 shares of common stock. The purchase price for each unit was $2.81. The warrants were exercisable upon issuance, expire seven years from the date of issuance, and have an exercise price of $2.28 per share, equal to 100% of the closing bid price of ARCA’s common stock on the Nasdaq Capital Market on January 22, 2013.

In connection with this transaction, the Company agreed that, subject to certain exceptions, it would not, while the warrants are outstanding, effect or enter into an agreement to effect any issuance of common stock or securities convertible into, exercisable for or exchangeable for common stock in a “variable rate transaction,” which means a transaction in which the Company issues or sells any convertible securities either (A) at a conversion price, exercise price or exchange rate or other price that is based upon and/or varies with the trading prices of, or quotations for, the shares of common stock at any time after the initial issuance of such convertible securities, or (B) with a conversion, exercise or exchange price that is subject to being reset at some future date after the initial issuance of the convertible securities or upon the occurrence of the specified or contingent events directly or indirectly related to our business or the market for our common stock. In addition, the Company agreed that, subject to certain exceptions, if it issues securities within one year following the closing of the offering, each investor would have the right to purchase its pro rata share of a specified portion of the securities in the future offering on the same terms, conditions and price provided for in the proposed issuance of securities.

Registered Direct Offering

On January 31, 2013, the Company entered into a subscription agreement with certain institutional investors (the “Investors”) in connection with its Registered Direct public offering, pursuant to which the Company sold an aggregate of 164,636 shares of its common stock and warrants to purchase up to 65,855 additional shares of its common stock to the Investors for aggregate gross proceeds of approximately $730,000, before deducting placement agent fee and other estimated offering expenses payable by the Company. The net proceeds to the Company were approximately $616,000, and the offering closed on February 4, 2013.

The common stock and warrants were sold in units consisting of one share of common stock and a warrant to purchase 0.40 shares of common stock. The purchase price for each unit was $4.43. The warrants were exercisable upon issuance, expire five years from the date of issuance, and have an exercise price of $4.13 per share, equal to the closing bid price of ARCA’s common stock on the Nasdaq Capital Market on January 31, 2013. The offering was effected as a takedown off the Company’s Registration Statement on Form S-3, as amended, which became effective on April 4, 2011, pursuant to a prospectus supplement filed with the Securities and Exchange Commission on February 1, 2013. The warrants provide for cashless exercise and settlement in unregistered shares if there is no effective registration statement registering, or the prospectus contained therein is not available for, the issuance of the shares of common stock underlying the warrants at the time of exercise.

Public Offering

On June 4, 2013, the Company sold shares of its Series A Convertible Preferred Stock (Preferred Stock) and warrants to purchase common stock in a public offering for aggregate gross proceeds of $20.0 million. The Company issued 125,000 shares of Preferred Stock and warrants to purchase up to 6,250,000 shares of common stock at a purchase price of $160 per share of Preferred Stock. The net proceeds, after deducting placement agent fees and other offering expenses payable by the Company, were approximately $17.9 million. ARCA’s Director and Chief Executive Officer participated in the offering, purchasing 781 shares of Preferred Stock and warrants to purchase 39,050 shares of common stock.

Each share of Preferred Stock was initially convertible into 100 shares of the Company’s common stock at any time at the option of the holder. Each share of Preferred Stock had a liquidation preference of $.001 per share. The shares of Preferred Stock had no preferential dividends or redemption rights, and no voting rights except as required by law. As of December 31, 2013, 125,000 shares of the Preferred Stock had been converted into 12,500,000 shares of ARCA common stock.

Each purchaser in the offering was issued a warrant to purchase 50 shares of the Company’s common stock for each share of Preferred Stock purchased. The warrants have an exercise price of $1.60 per share, will expire on the five year anniversary of the date of issuance, and were exercisable immediately upon issuance, provided that the holder will be prohibited from exercising the warrants if, as a result of such exercise, the holder, together with its affiliates, would beneficially own more than 9.99% of the total number of shares of common stock then issued and outstanding.

The securities were sold pursuant to a placement agreement and have been registered under the Securities Act of 1933 pursuant to the Company’s Registration Statement on Form S-1, as amended (No.333-187508), which was declared effective by the Securities and Exchange Commission on May 29, 2013, and the Preferred Stock and Warrants were offered and sold pursuant to a prospectus dated May 30, 2013.

In connection with the Preferred Stock financing, the Company recorded a non-cash dividend of approximately $2.0 million to recognize the intrinsic value of the embedded beneficial conversion feature. Typically, such a deemed dividend would be represented as a reduction in a company’s retained earnings and an increase in additional paid in capital in recognition of the reapportionment of common shareholder value to the preferred stock purchasers. However, since ARCA has an accumulated deficit, the deemed dividend is recognized by a reapportionment of additional paid in capital from common shareholders to additional paid in capital of preferred stock purchasers, which are combined in the Company’s statement of stockholders’ equity.

2014 Equity Financing

Subsequent to December 31, 2013, the Company completed the following equity financing transaction:

Registered Direct Offering

On February 3, 2014, the Company agreed to sell to certain investors an aggregate of 5,116,228 shares of the Company’s common stock and warrants to purchase an aggregate of 1,279,057 shares of the Company’s common stock at a purchase price of $1.70 per share of Common Stock, for aggregate gross proceeds of approximately $8.7 million, before deducting placement agent fees and other offering related expenses. The offering closed on February 7, 2014, and the net proceeds to the Company were approximately $7.9 million.

The common stock and warrants were sold in combination consisting of one share of common stock and a warrant to purchase 0.25 shares of common stock.. The warrants were exercisable upon issuance, expire five years from the date of issuance, and have an exercise price of $2.125 per share, equal to 125% of the closing bid price of ARCA’s common stock on the Nasdaq Capital Market on February 3, 2014. The offering was effected as a takedown off the Company’s Registration Statement on Form S-3, as amended, which became effective on April 4, 2011, pursuant to a prospectus supplement filed with the Securities and Exchange Commission on February 4, 2014. The warrants provide for cashless exercise and settlement in unregistered shares if there is no effective registration statement registering, or the prospectus contained therein is not available for, the issuance of the shares of common stock underlying the warrants at the time of exercise.

Warrants

As of December 31, 2013, warrants to purchase 8,147,484 shares of common stock were outstanding at exercise prices ranging from $1.60 to $116.89, with a weighted average exercise price per share of $2.32. These warrants, which were granted as part of various financing and business agreements, expire at various times between October 2016 and January 2020. Warrants were recorded in additional paid-in capital at their estimated fair market value at the date of grant using the Black-Scholes option-pricing model.