FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * Cross Atlantic Capital Partners, Inc.   2. Issuer Name and Ticker or Trading Symbol Rubicon Technology, Inc. [RBCN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) FIVE RADNOR CORPORATE CENTER, SUITE 555, 100 MATSONFORD ROAD 3. Date of Earliest Transaction (Month/Day/Year) 04/25/2013 (Street) RADNOR, PA 19087 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock               15,781 I See footnotes. (1) (2) Common Stock 04/25/2013   S(3)   225,000 D $ 7.4506 (4) 4,779,742 (5) D   Common Stock 04/26/2013   S(3)   61,891 D $ 7.5279 (6) 4,717,851 (7) D

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Cross Atlantic Capital Partners, Inc. FIVE RADNOR CORPORATE CENTER, SUITE 555 100 MATSONFORD ROAD RADNOR, PA 19087		X
CROSS ATLANTIC TECHNOLOGY FUND L P FIVE RADNOR CORPORATE CENTER, SUITE 555 100 MATSONFORD ROAD RADNOR, PA 19087		X
XATF Management, L.P. FIVE RADNOR CORPORATE CENTER, SUITE 555 100 MATSONFORD ROAD RADNOR, PA 19087		X
CROSS ATLANTIC TECHNOLOGY FUND II LP FIVE RADNOR CORPORATE CENTER, SUITE 555 100 MATSONFORD ROAD RADNOR, PA 19087		X
XATF MANAGEMENT II LP FIVE RADNOR CORPORATE CENTER, SUITE 555 100 MATSONFORD ROAD RADNOR, PA 19087		X
CROSS ATLANTIC CAPITAL PARTNERS II INC FIVE RADNOR CORPORATE CENTER, SUITE 555 100 MATSONFORD ROAD RADNOR, PA 19087		X
CO INVESTMENT 2000 FUND LP FIVE RADNOR CORPORATE CENTER, SUITE 555 100 MATSONFORD ROAD RADNOR, PA 19087		X
Co-Invest Management LP FIVE RADNOR CORPORATE CENTER, SUITE 555 100 MATSONFORD ROAD RADNOR, PA 19087		X
Co-Invest Capital Partners Inc FIVE RADNOR CORPORATE CENTER, SUITE 555 100 MATSONFORD ROAD RADNOR, PA 19087		X

Signatures

/s/ Donald R. Caldwell, Authorized Officer		04/29/2013
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	These securities are held by Donald R. Caldwell ("Caldwell"), a director of the Issuer, who is the owner and director of Cross Atlantic Capital Partners, Inc., which is the general partner of XATF Management L.P., which is the general partner of Cross Atlantic Technology Fund, L.P. Caldwell is a director, shareholder and officer of Cross Atlantic Capital Partners II, Inc., which is the general partner of XATF Management II, L.P., which is the general partner of Cross Atlantic Technology Fund II, L.P. Caldwell is a shareholder, director and officer of Co-Invest Capital Partners, Inc., which is the general partner of Co-Invest Management, L.P., which is the general partner of The Co-Investment 2000 Fund, L.P. Cross Atlantic Technology Fund, L.P, Cross Atlantic Technology Fund II, L.P. and The Co-Investment 2000 Fund, L.P. are collectively referred to as the "Funds". (Continued in footnote 2)
(2)	Under the terms of the applicable partnership agreements of the Funds, Caldwell is deemed to hold these securities for the benefit of the Funds, which are entitled to receive the net economic benefit of the securities as a credit against the management fees owed by the funds to Cross Atlantic Capital Partners, Inc. The Funds disclaim beneficial ownership of the securities except to the extent of their pecuniary interest therein.
(3)	Sales effected pursuant to a Rule 10b5-1 trading plan adopted on February 25, 2013.
(4)	The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.20 to $7.80 inclusive. The reporting persons undertake to provide the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price set forth within the ranges set forth in the footnotes to this Form 4.
(5)	Consists of shares directly held by the Funds as follows: Cross Atlantic Technology Fund, L.P. holds 61,891 shares of common stock, Cross Atlantic Technology Fund II, L.P. holds 2,230,198 shares of common stock and The Co-Investment 2000 Fund, L.P. holds 2,487,653 shares of common stock.
(6)	The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.35 to $7.658 inclusive. The reporting persons undertake to provide the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price set forth within the ranges set forth in the footnotes to this Form 4.
(7)	Consists of shares directly held by the Funds as follows: Cross Atlantic Technology Fund II, L.P. holds 2,230,198 shares of common stock and The Co-Investment 2000 Fund, L.P. holds 2,487,653 shares of common stock.

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