Exhibit 4.73



STOCK OPTION AGREEMENT



This STOCK OPTION AGREEMENT
(the “Agreement”) is made as of September 11, 2014 (the “Execution Date”),
by and between Prime Acquisition Corp., a Cayman Islands exempted company (the “Company”), and Monica
Sironi (the “Optionee”).



W I T N E S S E T H:



In consideration of the
premises and mutual covenants contained herein and for other good and valuable consideration, the receipt, validity and sufficiency
of which is hereby acknowledged, the parties agree as follows:



1.	Grant of Option.
Subject to the terms and conditions of this Agreement, the Company confirms that it granted to the Optionee the right (the “Option”)
to purchase all or any part of an aggregate of 2,500 (two thousand and five hundred) ordinary shares of the Company, par value
$0.001 per share (“Common Stock”).



2.	Vesting Schedule.
This Option shall vest based on activities and/or services performed, as set out in Addendum A.



3.	Exercise Price.
The price of each share of Common Stock purchased pursuant to this Option shall be U.S. $1.80.



4.	Exercise of
Option. The Optionee may exercise the Option, in whole or in part, with respect to any whole number of vested shares of Common
Stock subject to the Option. The Optionee shall exercise the Option by giving the Company written notice, in a form prescribed
by the Company. Such notice shall specify the number of shares of Common Stock to be purchased and shall be accompanied by payment,
in U.S. dollars, in cash, by wire transfer of immediately available funds, or by certified check or by official bank check, of
an amount equal to the Option exercise price per share of Common Stock, multiplied by the number of shares of Common Stock as to
which the Option is being exercised; provided, however, that (i) [this Option may be exercised on a cashless basis, in whole or
in part, in accordance with the Cashless Exercise Formula (as defined below), and (ii) the purchase price may be paid by the delivery
of funds equal to the purchase price by a broker, in accordance with Regulation T promulgated by the Board of Governors of the
Federal Reserve System or as otherwise may be permissible by law. The board of directors of the Company (the “Board”)
may impose from time to time such limitations as it deems appropriate on the exercise of the Option.



For purposes of this
Agreement, the term “Cashless Exercise Formula” means:

N’= (N x (P - E))
/ P

where:

N’ =	the adjusted
number of shares of Common Stock issuable upon cashless exercise of the Option.

N =	the current number
of shares of Common Stock issuable upon exercise of the Option.

E =	the Exercise Price
on the date of cashless exercise of the Option.

P =	the average reported
last sales price of the Common Stock for the last 10 trading days ending on the third business day prior to the date on which notice
of cashless exercise is given.





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5.	Delivery of
Common Stock Certificate. Subject to Section 6, as soon as practicable after receipt of the notice and payment referred to
in Section 4 above, the Company shall deliver to the Optionee (or, in the case of a broker financed exercise described in Section
4, to the broker) a certificate or certificates for such shares of Common Stock purchased pursuant to the Option; provided, however,
that the time of such delivery may be postponed by the Company for such period of time as the Company may require for compliance
with any law, rule or regulation applicable to the issuance or transfer of shares of Common Stock.



6.	Payment of Taxes.
Prior to or concurrently with delivery by the Company to the Optionee of a certificate or certificate(s) representing such shares
of Common Stock, the Optionee shall, if required by the IRS, upon notification of the amount due, promptly pay or cause to be paid,
in cash, any amount necessary to satisfy any tax requirements (or otherwise satisfy such requirements in a manner satisfactory
to the Company).



7.	Termination
of Option. This Option and all rights of the Optionee to purchase shares of Common Stock hereunder shall terminate on September
15, 2019 (the “Expiration Date”) unless terminated earlier in accordance with the terms hereof.



8.	Notice.
All notices, request, demands, waivers and communications required or permitted to be given hereunder shall be in writing and shall
be delivered in person or mailed, certified or registered mail with postage prepaid, or sent by facsimile, as follows:



To Company:
Prime Acquisition Corp.

No. 322, Zhongshan East Road,

Shijiazhuang, Hebei Province, 050011

People’s Republic of China
Attn: Chief Executive Officer

To Optionee:
Monica Sironi

Via C. Cantu 10,

23889 S. Maria Hoe (LC), Italy

m.sironi@magfin.net

c/o tel.: +39.02.72.73.34.00
c/o fax: +39.02.72.73.34.01



or to such other address or to the attention of such other person
as the recipient party shall have specified by prior written notice to the sending party. In the case of mailing, all such notices,
requests, demands, waivers and communications shall be deemed to have been received on the third business day after the date of
the mailing. In the case of facsimile after 5:00 P.M. local time at the place of delivery or on a day that is not a business day,
all such notices, requests, demands, waivers and communications shall be deemed to have been received on the next business day.





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9.	Certain Adjustments.



(a)	In the event
that the Company or the division, subsidiary or other affiliated entity for which the Optionee performs services is sold (including
a stock or an asset sale), spun off, merged, consolidated, reorganized or liquidated, the Board may determine that (i) the Option
shall be assumed, or a substantially equivalent Option shall be substituted, by an acquiring or succeeding entity (or an affiliate
thereof) on such terms as the Board determines to be appropriate; (ii) upon written notice to the Optionee, provide that the Option
shall terminate immediately prior to the consummation of the transaction unless exercised by the Optionee within a specified period
following the date of the notice (such period of time to be no less than 20 days); (iii) in the event of a sale or similar transaction
under the terms of which holders of Common Stock receive a payment for each share of Common Stock surrendered in the transaction
(the “Sales Price”), make or provide for a payment to each Optionee equal to the amount by which (A)
the Sales Price times the number of shares of Common Stock subject to the Option (to the extent such Option is then exercisable)
exceeds (B) the aggregate exercise price for all such shares of Common Stock; or (iv) may make such other equitable adjustments
as the Board deems appropriate.



(b)	In the event
of any stock dividend or split, recapitalization, combination, exchange or similar change affecting the Common Stock, the Board
shall make any or all of the following adjustments as it deems appropriate to equitably reflect such event: (i) adjust the
option price to be paid for any or all shares subject to this Agreement, (ii) adjust the number of shares of Common Stock
(or such other security as is designated by the Board) subject to this Agreement and (iii) make any other equitable adjustments
or take such other equitable action as the Board, in its discretion, shall deem appropriate.



(c)	Any and all
adjustments or actions taken by the Board pursuant to this Section shall be conclusive and binding for all purposes.



10.	No Restriction
on the Right of the Company to Effect Corporate Changes. The Option granted hereunder shall not affect in any way the right
or power of the Company or its stockholders to make or authorize any or all adjustments, recapitalizations, reorganizations or
other changes in the Company’s capital structure or its business, or any merger or consolidation of the Company, or any issue
of stock or of options, warrants or rights to purchase stock or of bonds, debentures, preferred or prior preference stocks whose
rights are superior to or affect the Common Stock or the rights of holders thereof or which are convertible into or exchangeable
for Common Stock, or the dissolution or liquidation of the Company, or any sale or transfer of all or any part of its assets or
business, or any other corporate act or proceeding, whether of a similar character or otherwise.



11.	No Shareholder
Rights. The Optionee shall have no rights as a shareholder of the Company with respect to shares of Common Stock subject to
the Option until payment for such shares shall have been made in full and until the date of the issuance of share certificates
for such shares of Common Stock.



12.	Nontransferability.



(a)	Except as provided
in paragraph (b) of this Section 12, or by will or the laws of descent and distribution, the Option is not transferable, and may
be exercised only by the Optionee. In the event of any attempt by the Optionee to transfer, assign, pledge, hypothecate or otherwise
dispose of the Option or of any right hereunder, except as provided for herein, or in the event of the levy of any attachment,
execution or similar process upon the rights or interest hereby conferred, the Company may terminate the Option by notice to the
Optionee and it shall thereupon become null and void.





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(b)	Notwithstanding
paragraph (a), the Optionee may transfer the Option, by gift or a domestic relations order, to a family member of the Optionee.



(c)	Notwithstanding
paragraphs (a) or (b), the Optionee may transfer the Option with the express, prior written consent of the Company, which consent
may be withheld for any reason or for no reason.



13.	Representations
By and Covenants of Optionee.



The following representations,
warranties and covenants by Optionee are made as of the date of this Agreement and, unless stated otherwise herein, are also made
as of each date of exercise of this Agreement.



(a)	If applicable,
the Optionee understands and consents to the placement of a legend on any certificate or other document evidencing the Shares stating
that they have not been registered under the Securities Act and setting forth or referring to the restrictions on transferability
and sale thereof.



(b)	Optionee hereby
represents that the address of Optionee furnished by him on the signature page of this Agreement is accurate and that said address
is the Optionee’s principal residence. Optionee understands that the Company is relying on the accuracy of this representation
for purposes of its compliance with United States federal securities laws and state “blue sky” laws.



(c)	This Agreement
has been duly executed and delivered by the Optionee and constitutes the legal, valid and binding obligation of the Optionee, enforceable
in accordance with its terms.



14.	NSO. It
is intended that this Option shall be a non-qualified stock option and shall not constitute an incentive stock option for purposes
of Section 422 of the Internal Revenue Code of 1986, as amended.



15.	Compliance
with Law; Registration of Shares.



(a)	The Option grant
provided hereunder shall be subject to all applicable laws, rules, and regulations of any applicable jurisdiction or authority
or agency thereof and to such approvals by any regulatory or governmental authority or agency or securities exchange which, in
the opinion of Company’s counsel, may be required or appropriate.



(b)	Notwithstanding
any other provision of this Agreement, the Company shall not be required to issue or deliver any certificate or certificates for
shares of Common Stock under this Agreement prior to fulfillment of all of the following conditions:



(i)	Effectiveness
of any registration or other qualification of such shares of the Company under any law or regulation of any applicable jurisdiction,
authority or agency that the Board, in its absolute discretion or upon the advice of counsel, deems necessary or advisable; and



(ii)	Grant
of any other consent, approval or permit from any applicable jurisdiction or authority or agency thereof or securities exchange
which the Board shall, in its absolute discretion or upon the advice of counsel, deem necessary or advisable.





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The Company shall use
all reasonable efforts to obtain any consent, approval or permit described above.



16.	Headings.
The headings of sections and subsections herein are included solely for convenience of reference and shall not affect the meaning
of any of the provisions of this Agreement.



17.	Severability.
In the event that any one or more provisions of this Agreement, or any action taken pursuant to this Agreement, should, for any
reason, be unenforceable or invalid in any respect under the laws of the United States, any state of the United States or any other
jurisdiction, such unenforceability or invalidity shall not affect any other provision of this Agreement, but in such particular
jurisdiction and instance this Agreement shall be construed as if such unenforceable or invalid provision had not been contained
therein or if the action in question had not been taken thereunder.



18.	Board Determinations.
In the event that any question or controversy shall arise with respect to the nature, scope or extent of any one or more rights
conferred by the Option, or any provision of this Agreement, the good faith determination by the Board of the rights of the Optionee
shall be conclusive, final and binding upon the Optionee and upon any other person who shall assert any right pursuant to this
Option.



19.	Governing Law.
This Agreement and all rights hereunder shall be construed in accordance with and governed by the internal laws of the State of
New York applicable to agreements made and to be performed within the State of New York, without giving effect to any choice-of-law
provisions thereof that would compel the application of the substantive laws of any other jurisdiction.



20.	Jurisdiction;
Venue. The Optionee hereby agrees that any action, proceeding or claim against it arising out of, or relating in any way to
this Agreement shall be brought and enforced in the courts of the State of New York or of the United States of America for the
Southern District of New York, and irrevocably submits to such jurisdiction, which jurisdiction shall be exclusive. The Optionee
hereby waives any objection to such exclusive jurisdiction and that such courts represent an inconvenient forum. Any process or
summons to be served upon the Optionee may be served by transmitting a copy thereof by registered or certified mail, return receipt
requested, postage prepaid, addressed to it at the address set forth herein. Such mailing shall be deemed personal service and
shall be legal and binding upon the Optionee in any action, proceeding or claim. The Company and the Optionee agree that the prevailing
party(ies) in any such action shall be entitled to recover from the other party(ies) all of its reasonable attorneys’ fees
and expenses relating to such action or proceeding and/or incurred in connection with the preparation therefor.



21.	Amendment.
This Agreement may not be changed or modified except by an instrument in writing signed by both of the parties hereto.



22.	Counterparts.
This Agreement may be executed in one or more counterparts, each of which shall be deemed to be an original, all of which together
will constitute one and the same instrument.





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IN WITNESS WHEREOF, the
Company and the Optionee have executed this Agreement effective as of the date first written above.





| | PRIME ACQUISITION CORP.





By: /s/ Diana Liu

Name: DIANA LIU

Title: CHAIRMAN







OPTIONEE:



/s/ Monica Sironi

Monica Sironi





Address:

Via C. Cantu 10,

23889 S. Maria Hoe (LC), Italy

m.sironi@magfin.net
| | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------













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ADDENDUM A

VESTING SCHEDULE





The Stock Option granted in the Stock Option Agreement shall
vest based on the following formula:



6.25% of the Stock Option granted shall vest every three months
from the date of the grant;



Vesting shall stop when the Optionee ceases her position with
the Company.





















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