13D Filing: Bandera Partners and Rubicon Technology Inc. (RBCN)

The following constitutes the Schedule 13D filed
by the undersigned (the “Schedule 13D”).

Item 1.

Security and Issuer.

This statement relates
to the Common Stock, $0.001 par value (the “Shares”), of Rubicon Technology, Inc., a Delaware corporation (the “Issuer”).
The address of the principal executive offices of the Issuer is 900 East Green Street, Bensenville, Illinois 60106.

Item 2.

Identity and Background.

(a)       This
statement is filed by:

(i)

Bandera Master Fund L.P., a Cayman Islands exempted limited partnership (“Bandera Master Fund”);

(ii)

Bandera Partners LLC, a Delaware limited liability company (“Bandera Partners”);

(iii)

Gregory Bylinsky; and

(iv)

Jefferson Gramm.

Each of the foregoing
is referred to as a “Reporting Person” and collectively as the “Reporting Persons.” Each of the Reporting
Persons is party to that certain Joint Filing Agreement as further described in Item 6. Accordingly, the Reporting Persons are
hereby filing a joint Schedule 13D.

Bandera Partners is
the investment manager of Bandera Master Fund. Bandera Master Fund has granted to Bandera Partners the sole and exclusive authority
to vote and dispose of the Shares held directly by Bandera Master Fund. Each of Messrs. Bylinsky and Gramm are Managing Partners,
Managing Directors and Portfolio Managers of Bandera Partners. By virtue of these relationships, each of Bandera Partners and Messrs.
Bylinsky and Gramm may be deemed to beneficially own the Shares owned directly by Bandera Master Fund.

(b)       The
address of the principal office of each of the Reporting Persons is 50 Broad Street, Suite 1820, New York, New York 10004.

(c)       The
principal business of Bandera Master Fund is investing in securities. The principal business of Bandera Partners is serving as
the investment manager of Bandera Master Fund. Each of Messrs. Bylinsky and Gramm are Managing Partners, Managing Directors and
Portfolio Managers of Bandera Partners. Mr. Gramm also serves as a director of the Issuer.

(d)       No
Reporting Person has, during the last five years, been convicted in a criminal proceeding (excluding traffic violations or similar
misdemeanors).

(e)       No
Reporting Person has, during the last five years, been party to a civil proceeding of a judicial or administrative body of competent
jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations
of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to
such laws.