Sec Form 4 Filing - Chang Michael N @ OPTIMER PHARMACEUTICALS INC - 2013-09-04

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 Chang Michael N 2. Issuer Name and Ticker or Trading Symbol OPTIMER PHARMACEUTICALS INC [ OPTR] 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) C/O OPTIMER PHARMACEUTICALS, INC., 101 HUDSON STREET 3. Date of Earliest Transaction (MM/DD/YY) 09/04/2013 (Street) JERSEY CITY, NJ07302 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 Common stock 09/04/2013 M 100,000 A $ 9.7 948,956 D Common stock 09/04/2013 M 70,000 A $ 6.9 1,018,956 D Common stock 09/04/2013 M 8,000 A $ 9.56 1,026,956 D Common stock 09/04/2013 M 4,615 A $ 2.17 342,761 I by spouse Common stock 09/04/2013 M 30,000 A $ 9.7 372,761 I by spouse Common stock 09/04/2013 M 30,000 A $ 6.9 402,761 I by spouse Common stock 09/04/2013 M 30,000 A $ 10.75 432,761 I by spouse Common stock 09/04/2013 M 9,000 A $ 11.41 441,761 I spouse

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 Stock option (right to buy) $ 9.7 09/04/2013 M 100,000 ( 1 ) 03/29/2017 Common stock 100,000 $ 0 0 D Stock option (right to buy) $ 6.9 09/04/2013 M 70,000 ( 2 ) 01/04/2018 Common stock 70,000 $ 0 0 D Stock option (right to buy) $ 9.56 09/04/2013 M 8,000 ( 3 ) 12/01/2020 Common stock 8,000 $ 0 2,000 D Stock option (right to buy) $ 2.17 09/04/2013 M 4,615 ( 4 ) 09/13/2016 Common stock 4,615 $ 0 0 I by spouse Stock option (right to buy) $ 9.7 09/04/2013 M 30,000 ( 1 ) 03/29/2017 Common stock 30,000 $ 0 0 I by spouse Stock option (right to buy) $ 6.9 09/04/2013 M 30,000 ( 5 ) 01/04/2018 Common stock 30,000 $ 0 0 I by spouse Stock option (right to buy) $ 10.75 09/04/2013 M 30,000 ( 6 ) 01/08/2019 Common stock 30,000 $ 0 0 I by spouse Stock option (right to buy) $ 11.41 09/04/2013 M 9,000 ( 7 ) 01/26/2021 Common stock 9,000 $ 0 11,000 I by spouse

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Chang Michael N C/O OPTIMER PHARMACEUTICALS, INC. 101 HUDSON STREET JERSEY CITY, NJ07302 X Signatures Michael N. Chang 09/05/2013 Signature of Reporting Person Date

Explanation of Responses:

( 1 )25% of the options vested on March 29, 2008 and 1/48 of the options vested each month thereafter. ( 2 )25% of the options vested on January 4, 2009 and 1/48 of the options vested each month thereafter. ( 3 )1/12th of the shares subject to the stock option vested and became exercisable each month, commencing February 1, 2011. ( 4 )25% of the options vested on October 1, 2007 and 1/48 of the options vested each month thereafter. ( 5 )On January 4, 2008, Mrs. Che was granted an option to purchase 30,000 shares of common stock. 1/4 of the shares subject to the option vested on January 4, 2009. Thereafter, the remaining shares subject to the option were scheduled to vest and become exercisable in 36 equal monthly installments subject to Mrs. Che continuing to be service provider on each such date. At the time of Mrs. Che's separation in January 2012, the option: (i) had vested as to 29,375 shares; and (ii) was accelerated as to 625 shares in accordance with her separation agreement. ( 6 )On January 8, 2009, Mrs. Che was granted an option to purchase 30,000 shares of common stock. 1/4 of the shares subject to the option vested on January 8, 2010. Thereafter, the remaining shares subject to the option were scheduled to vest and become exercisable in 36 equal monthly installments subject to Mrs. Che continuing to be service provider on each such date. At the time of Mrs. Che's separation in January 2012, the option: (i) had vested as to 21,875 shares; and (ii) was accelerated as to 8,125 shares in accordance with her separation agreement. ( 7 )On January 26, 2011, Mrs. Che was granted an option to purchase 20,000 shares of common stock. 1/4 of the shares subject to the option vested on January 26, 2012. Thereafter, the remaining shares subject to the option were scheduled to vest and become exercisable in 36 equal monthly installments subject to Mrs. Che continuing to be service provider on each such date. At the time of Mrs. Che's separation in January 2012, the option: (i) had no shares vested; and (ii) was accelerated as to 20,000 shares in accordance with her separation agreement.

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