| Stockholders' Equity | Note 11. Stockholders’ Equity In September 2015, the Company filed
with the SEC a $75 million shelf registration statement on Form S-3 (the 2015 Shelf Registration Statement) (File No. 333-206789)
that allows the Company to issue any combination of common stock, preferred stock or warrants to purchase common stock or preferred
stock. This shelf registration was declared effective on September 25, 2015. The 2015 Shelf Registration Statement expired on September
25, 2018. In September 2018, the Company filed
with the SEC a new $75 million shelf registration statement on Form S-3 (the 2018 Shelf Registration Statement) (File No. 333-227236)
that allows the Company to issue any combination of common stock, preferred stock or warrants to purchase common stock or preferred
stock. This shelf registration was declared effective on October 12, 2018 and will expire three years from that date. Increase in the Number of Authorized
Shares At the 2016 Annual Meeting of Stockholders
of the Company in June 2016, the Company’s stockholders approved an increase in the number of the authorized shares of the
Company’s common stock from 75,000,000 shares to 112,500,000 shares. The number of the authorized shares of preferred stock
remains at 100,000 shares. The aggregate number of shares of all classes of stock that the Company may issue, after giving effect
to such amendment as approved by the stockholders, will be 112,600,000 shares. Reverse Stock Split On May 26, 2017, the Company effected
a 14-for-1 reverse stock split of its common stock which was made effective for trading purposes as of the commencement of trading
on May 30, 2017. As of that date, each 14 shares of issued and outstanding common stock and equivalents was consolidated into one
share of common stock. All shares have been restated to reflect the effects of the 14-for-1 reverse stock split. In addition, at
the market open on May 30, 2017, the Company’s common stock started trading under a new CUSIP number 15117N503 although the
Company’s ticker symbol, CLSN, remained unchanged. The reverse stock split was previously
approved by the Company’s stockholders at the 2017 Annual Meeting held on May 16, 2017, and the Company subsequently filed
a Certificate of Amendment to its Certificate of Incorporation to effect the stock consolidation. The primary reasons for the reverse
stock split and the amendment are:
● To increase the market price of the Company’s common stock making it more attractive to a broader range of institutional and other investors, and
● To provide the Company with additional capital resources and flexibility sufficient to execute its business plans including the establishment of strategic relationships with other companies and to ensure its ability to raise additional capital as necessary. Immediately prior to the reverse stock
split, the Company had 56,982,418 shares of common stock outstanding which consolidated into 4,070,172 shares of the Company’s
common stock. No fractional shares were issued in connection with the reverse stock split. Holders of fractional shares have been
paid out in cash for the fractional portion with the Company’s overall exposure for such payouts consisting of a nominal
amount. The number of outstanding options and warrants were adjusted accordingly, with outstanding options being reduced from approximately
2.4 million to approximately 0.2 million and outstanding warrants being reduced from approximately 33.5 million to approximately
2.4 million. October 2017 Underwritten Offering On October 27, 2017, the Company entered
into an underwriting agreement (the “Underwriting Agreement”) with Oppenheimer& Co. Inc. (the “Underwriter”),
relating to the issuance and sale (the “October 2017 Underwritten Offering”) of 2,640,000 shares (the “Shares”)
of the Company’s common stock, $0.01 par value per share (the “Common Stock”), and warrants to purchase an aggregate
of 1,320,000 shares of Common Stock. Each share of Common Stock is being sold together with 0.5 warrants (the “Investor Warrants”),
each whole Investor Warrant being exercisable for one share of Common Stock, at an offering price of $2.50 per share and related
Investor Warrants. Pursuant to the terms of the Underwriting
Agreement, the Underwriter agreed to purchase the Shares and related Investor Warrants from the Company at a price of $2.325 per
share and related Investor Warrants. Each Investor Warrant is exercisable six months from the date of issuance. The Investor Warrants
have an exercise price of $3.00 per whole share and expire five years from the date first exercisable. The Company received $6.6 million of
gross proceeds from the sale of the Shares and Investor Warrant. The October 2017 Underwritten Offering was made pursuant to the
2015 Shelf Registration Statement and the related prospectus supplement. The Company also issued to the Underwriter warrants to
purchase up to 66,000 shares of the Company’s common stock, such issuance being exempt from registration pursuant to Section
4(a)(2) of the Securities Act. Each Underwriter warrant is exercisable six months from the date of issuance, have an exercise price
of $2.87 per whole share, and expire five years from the date first exercisable . July 6, 2017 Common Stock Offering On July 6, 2017, the Company entered
into a securities purchase agreement with several investors, pursuant to which the Company agreed to issue and sell, in a registered
direct offering, an aggregate of 2,050,000 shares of common stock of the Company at an offering price of $2.07 per share for gross
proceeds of $4,243,500 before the deduction of the placement agent fee and offering expenses. In addition, the Company sold Pre-Funded
Series CCC Warrants to purchase 385,000 shares of common stock (and the shares of common stock issuable upon exercise of the Pre-Funded
Series CCC Warrants), in lieu of shares of common stock to the extent that the purchase of common stock would cause the beneficial
ownership of the Purchaser, together with its affiliates and certain related parties, to exceed 9.99% of our common stock. The
Pre-Funded Series CCC Warrants were sold at an offering price of $2.06 per share for gross proceeds of $793,100, are immediately
exercisable for $0.01 per share of common stock and do not have an expiration date. In a concurrent private placement, the Company
agreed to issue to each investor, for each share of common stock and pre-funded warrant purchased in the offering, a Series AAA
Warrant and Series BBB Warrant, each to purchase one share of common stock. The Series AAA Warrants are initially exercisable six
months following issuance and terminate five and one-half years following issuance. The Series AAA Warrants have an exercise price
of $2.07 per share and are exercisable to purchase an aggregate of 2,435,000 shares of common stock. The Series BBB Warrants are
immediately exercisable following issuance and terminate twelve months following issuance. The Series BBB Warrants have an exercise
price of $4.75 per share and are exercisable to purchase an aggregate of 2,435,000 shares of common stock. Subject to limited exceptions,
a holder of a Series AAA and Series BBB Warrant will not have the right to exercise any portion of its warrants if the holder,
together with its affiliates, would beneficially own in excess of 9.99% of the number of shares of common stock outstanding immediately
after giving effect to such exercise. During the fourth quarter of 2017, all 385,000 of the Series CCC Pre-Funded warrants were
exercised in full. On October 4, 2017, the Company entered
into letter agreements (the “Exercise Agreements”) with the holders of the Series AAA and Series BBB Warrants issued
in the July 6, 2017 Common Stock Offering (the “Exercising Holders”). The Exercise Agreements amended the Series AAA
Warrants to permit their immediate exercise. Prior to the execution of the Exercise Agreements, the Series AAA Warrants were not
exercisable until January 11, 2018. Pursuant to the Exercise Agreements, the Exercising Holders and the Company agreed that the
Exercising Holders would exercise all of their Existing Warrants with respect to 4,665,000 shares of Common Stock underlying such
Existing Warrants. The Series AAA Warrants and Series BBB Warrants were exercised at a price of $2.07 per share and $4.75 per share,
respectively, which were their respective original exercise prices. The Company received approximately $16.6 million in gross proceeds
from the sale of these warrants. The Exercise Agreements also provide
for the issuance of 1,166,250 Series DDD Warrants, each to purchase one share of Common Stock (the “Series DDD Warrants”).
The Series DDD Warrants have an exercise price $6.20, are exercisable one year following issuance and terminate six months after
they are initially exercisable. The Series DDD Warrants and the shares of Common Stock issuable upon the exercise of the Series
DDD Warrants were offered pursuant to the exemption provided in Section 4(a)(2) under the Securities Act or Rule 506(b) promulgated
thereunder. Pursuant to the Exercise Agreements, the Series DDD Warrants shall be substantially in the form of the Existing Warrants
and the Company will be required to register for resale the shares of Common Stock underlying the Series DDD Warrants. February 14, 2017 Public Offering On February 14, 2017, the Company entered
into a securities purchase agreement whereby it sold, in a public offering (the “February 2017 Public Offering”), an
aggregate of 1,384,704 shares of common stock of the Company at an offering price of $3.22 per share. In addition, the Company
sold Series AA Warrants (the “Series AA Warrants”) to purchase up to 1,177,790 shares of common stock and Pre-Funded
Series BB Warrants (the “Pre-Funded Series BB Warrants”) to purchase up to 185,713 shares of common stock. The Series
AA Warrants have an exercise price of $3.22 per share, have a five-year life and are immediately exercisable. The Pre-Funded Series
BB Warrants were offered at $3.08 per share, were immediately exercisable for $0.14 per share of common stock, do not have an expiration
date and were issued in lieu of shares of common stock to the extent that the purchase of common stock would cause the beneficial
ownership of the purchaser of such shares, together with its affiliates and certain related parties, to exceed 9.99% of our common
stock. The Company received approximately $5.0 million in gross proceeds before the deduction of the placement agent fees and offering
expenses (excluding any proceeds from the exercise of the warrants) in the February 2017 Public Offering. In connection with the February 2017
Public Offering, the Company filed with the SEC a registration statement on Form S-1 (Registration No. 333-215321) on December
23, 2016, as amended by Pre-Effective Amendment No. 1 filed with the Commission on January 20, 2017, as further amended by Pre-Effective
Amendment No. 2 filed with the Commission on February 13, 2017, as further amended by Pre-Effective Amendment No. 3 filed with
the Commission on February 13, 2017 and as further amended by Pre-Effective Amendment No. 4 filed with the Commission on February
14, 2017 for the registration of the securities issued and sold under the Securities Act of 1933, as amended. As of December 31, 2017, all 185,713
of the Series BB Pre-Funded warrants were exercised in full. During 2017, we received approximately $2.4 million from the exercise
of Series AA Warrants to purchase 747,254 shares of common stock. Reduced Exercise Price of Warrants On February 22, 2013, the Company entered
into a securities purchase agreement with certain investors pursuant to which the Company agreed, among other things, to issue
warrants (the “2013 Warrants”) to purchase up to 95,811 shares of our common stock at an exercise price of $74.34 per
share to such investors in a registered direct offering. On January 15, 2014, the Company entered into a securities purchase agreement
with certain investors pursuant to which the Company agreed, among other things, to issue warrants (the “2014 Warrants”)
to purchase up to 64,348 shares of our common stock at an exercise price of $57.40 per share to such investors in a registered
direct offering. On June 9, 2017, the Company entered into warrant exercise agreements (the “Exercise Agreements”)
with certain holders of the 2013 Warrants, the 2014 Warrants and the June 2016 Warrants (the “Exercising Holders”),
which Exercising Holders own, in the aggregate, warrants exercisable for 790,410 shares of our common stock. Pursuant to the Exercise
Agreements, the Exercising Holders and the Company agreed that the Exercising Holders would exercise their 2013 Warrants, the 2014
Warrants and the June 2016 Warrants with respect to 790,410 shares of our common stock underlying such warrants for a reduced exercise
price equal to $2.70 per share. The Company received aggregate gross proceeds of approximately $2.1 million from the exercise of
the 2013 Warrants, the 2014 Warrants and the June 2016 Warrants by the Exercising Holders. The reduced exercise price of the 2013
Warrants, the 2014 Warrants and the June 2016 Series C Warrants increased the fair value of the warrants by approximately $0.2
million. This increase in fair value is recorded as a deemed dividend in additional paid in capital due to the retained deficit
and it increased the net loss available to common shareholders on the consolidate statement of operations. On May 27, 2015, the Company entered
into a securities purchase agreement with certain investors pursuant to which the Company agreed, among other things, to issue
warrants (the “2015 Warrants”) to purchase up to 139,284 shares of the Company’s common stock at an exercise
price of $36.40 per share, to such investors in a registered direct offering. Between June 22, 2017 through June 26, 2017, the
Company and holders of the 2015 Warrants and the December 2016 Warrants (the “Exercising Investors”) entered into agreements
whereby the Company agreed that the Exercising investors would exercise their 2015 Warrants and the June 2016 Warrants with respect
to 506,627 shares of our common stock underlying such warrants for a reduced exercise price equal to $1.65 per share. The Company
received aggregate gross proceeds of approximately $0.8 million from the exercise of the 2015 Warrants and the June 2016 Warrants
by the Exercising Investors. The reduced exercise price of the 2015
Warrants increased the fair value of the warrants by approximately $0.1 million. This increase in fair value is recorded as a deemed
dividend in additional paid in capital due to the retained deficit and it increased the net loss available to common shareholders
on the consolidate statement of operations. Aspire Purchase Agreement On August 31, 2018, we entered into
a common stock purchase agreement (the “Aspire Purchase Agreement”) with Aspire Capital Fund, LLC (“Aspire Capital”)
which provides that, upon the terms and subject to the conditions and limitations set forth therein, Aspire Capital is committed
to purchase up to an aggregate of $15.0 million of shares of the Company’s common stock over the 24-month term of the Aspire
Purchase Agreement. On October 12, 2018, the Company filed with the SEC a prospectus supplement to the 2018 Shelf Registration
Statement registering all of the shares of common stock that may be offered to Aspire Capital from time to time. Under the Aspire Purchase Agreement,
on any trading day selected by the Company, the Company has the right, in its sole discretion, to present Aspire Capital with a
purchase notice (each, a “Purchase Notice”), directing Aspire Capital (as principal) to purchase up to 100,000 shares
of the Company’s common stock per business day, up to $15.0 million of the Company’s common stock in the aggregate
at a per share price (the “Purchase Price”) equal to the lesser of:
● the lowest sale price of the Company’s common stock on the purchase date; or
● the arithmetic average of the three (3) lowest closing sale prices for the Company’s common stock during the ten (10) consecutive trading days ending on the trading day immediately preceding the purchase date. The Company and Aspire Capital also
may mutually agree to increase the number of shares that may be sold to as much as an additional 2,000,000 shares per business
day. In addition, on any date on which the
Company submits a Purchase Notice to Aspire Capital in an amount equal to at least 100,000 shares, the Company also has the right,
in its sole discretion, to present Aspire Capital with a volume-weighted average price purchase notice (each, a “VWAP Purchase
Notice”) directing Aspire Capital to purchase an amount of stock equal to up to 30% of the aggregate shares of the Company’s
common stock traded on its principal market on the next trading day (the “VWAP Purchase Date”), subject to a maximum
number of shares the Company may determine. The purchase price per share pursuant to such VWAP Purchase Notice is generally 97%
of the volume-weighted average price for the Company’s common stock traded on its principal market on the VWAP Purchase Date. The Purchase Price will be adjusted
for any reorganization, recapitalization, non-cash dividend, stock split, or other similar transaction occurring during the period(s)
used to compute the Purchase Price. The Company may deliver multiple Purchase Notices and VWAP Purchase Notices to Aspire Capital
from time to time during the term of the Purchase Agreement, so long as the most recent purchase has been completed. There are no trading volume requirements
or restrictions under the Purchase Agreement, and the Company will control the timing and amount of sales of the Company’s
common stock to Aspire Capital. Aspire Capital has no right to require any sales by the Company but is obligated to make purchases
from the Company as directed by the Company in accordance with the Purchase Agreement. There are no limitations on use of proceeds,
financial or business covenants, restrictions on future fundings, rights of first refusal, participation rights, penalties or liquidated
damages in the Purchase Agreement. In consideration for entering into the Purchase Agreement, concurrently with the execution of
the Purchase Agreement, the Company issued to Aspire Capital 164,835 shares of the Company’s common stock (the “Commitment
Shares”). The Company’s policy is to record specific incremental costs directly attributable to an offering as a charge
against the gross proceeds, if any, when the offering becomes effective. These Commitment Shares valued at $450,000 were recorded
in September 2018 as costs of equity financing and charged against additional paid-in capital. The Aspire Purchase Agreement may
be terminated by the Company at any time, at its discretion, without any cost to the Company. Aspire Capital has agreed that neither
it nor any of its agents, representatives and affiliates shall engage in any direct or indirect short-selling or hedging of the
Company’s common stock during any time prior to the termination of the Purchase Agreement. Any proceeds from the Company
receives under the Aspire Purchase Agreement are expected to be used for working capital and general corporate purposes. Controlled Equity Offering On February 1, 2013, the Company entered
into a Controlled Equity Offering SM Sales Agreement (the “ATM Agreement”) with Cantor Fitzgerald & Co., as sales
agent (“Cantor”), pursuant to which Celsion could offer and sell, from time to time, through Cantor, shares of our
common stock having an aggregate offering price of up to $25.0 million (the “ATM Shares”) pursuant to the 2015 Shelf
Registration Statement. Under the ATM Agreement, Cantor may sell ATM Shares by any method deemed to be an “at-the-market”
offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended, including sales made directly on The
NASDAQ Capital Market, on any other existing trading market for our common stock or to or through a market maker. On October 10,
2018, the Company delivered notice to Cantor terminating the ATM effective as of October 20, 2018. The Company has no further
obligations under the Sales Agreement. From February 1, 2013 through September 30, 2018, the Company sold and issued an aggregate
of 1,784,396 shares of common stock under the ATM Agreement, receiving approximately $12.8 million in gross proceeds. |
