Sec Form 4 Filing - MARSHALL LYDIA MICHEAUX @ Seagate Technology plc - 2012-02-07

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 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 MARSHALL LYDIA MICHEAUX 2. Issuer Name and Ticker or Trading Symbol Seagate Technology plc [ STX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) SEAGATE TECHNOLOGY PLC, 10200 S. DE ANZA BOULEVARD 3. Date of Earliest Transaction (MM/DD/YY) 02/07/2012 (Street) CUPERTINO, CA95014 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ 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 (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 Ordinary Shares 02/07/2012 M 25,000 A $ 14.31 69,166 D Ordinary Shares 02/07/2012 M 90,000 A $ 12.755 159,166 D Ordinary Shares 02/07/2012 S 115,000 D $ 26.7167 44,166 D

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 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 NQ Stock Options $ 14.31 02/07/2012 M 25,000 10/27/2006( 1 ) 10/27/2012 Ordinary Shares 25,000 $ 0 0 D NQ Stock Options $ 12.755 02/07/2012 M 90,000 04/29/2005( 2 ) 04/29/2014 Ordinary Shares 90,000 $ 0 0 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other MARSHALL LYDIA MICHEAUX SEAGATE TECHNOLOGY PLC 10200 S. DE ANZA BOULEVARD CUPERTINO, CA95014 X Signatures /S/ Roberta S. Cohen for Lydia M. Marshall 02/09/2012 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Options granted to the Reporting Person under the Issuer's 2004 Stock Compensation Plan are subject to a four-year vesting schedule. One-quarter of the option shares vested on October 27, 2006. The remaining option shares vested proportionally monthly ovr the 36 months following October 26, 2006. ( 2 )Options granted to the Reporting Person under the Issuer's 2001 Share Optioin Plan is subject to a four-year vesting schedule. One-quarter of the option shares vested on April 29, 2005. The remaining option shares vested proportionally monthly ovr the 36 months following April 29, 2005.

Remarks: .

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* 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).

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