Sec Form 4 Filing - TANG KEVIN C @ LA JOLLA PHARMACEUTICAL CO - 2021-05-24

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 TANG KEVIN C 2. Issuer Name and Ticker or Trading Symbol LA JOLLA PHARMACEUTICAL CO [ LJPC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 4747 EXECUTIVE DRIVE, SUITE 210 3. Date of Earliest Transaction (MM/DD/YY) 05/24/2021 (Street) SAN DIEGO, CA92121 4. If Amendment, Date Original Filed (MM/DD/YY) 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 (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 05/24/2021 P 104,403 A $ 3.6803 ( 1 ) 9,509,893 I ( 2 ) By LP ( 2 ) Common Stock 05/25/2021 P 95,597 A $ 3.7748 ( 3 ) 9,605,490 I ( 2 ) By LP ( 2 ) Common Stock 05/25/2021 P 31,782 A $ 3.8347 ( 4 ) 9,637,272 I ( 2 ) By LP ( 2 ) Common Stock 05/26/2021 P 166,932 A $ 4.2578 ( 5 ) 9,804,204 I ( 2 ) By LP ( 2 )

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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other TANG KEVIN C 4747 EXECUTIVE DRIVE, SUITE 210 SAN DIEGO, CA92121 X X TANG CAPITAL PARTNERS LP 4747 EXECUTIVE DRIVE, SUITE 210 SAN DIEGO, CA92121 X TANG CAPITAL MANAGEMENT LLC 4747 EXECUTIVE DRIVE, SUITE 210 SAN DIEGO, CA92121 X Hearne Michael S 4747 EXECUTIVE DRIVE, SUITE 210 SAN DIEGO, CA92121 Chief Financial Officer Signatures /s/ Kevin Tang 05/26/2021 Signature of Reporting Person Date /s/ Kevin Tang, Managing Member of Tang Capital Management, LLC, General Partner 05/26/2021 Signature of Reporting Person Date /s/ Kevin Tang, Managing Member 05/26/2021 Signature of Reporting Person Date /s/ Michael Hearne 05/26/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The prices reported in Column 4 are weighted-average prices. These shares were purchased in multiple transactions at prices ranging from $3.425 to $3.80. TheReporting Persons undertake to provide the Issuer, any security holder of the Issuer or the SEC Staff, upon request, full information regarding the number of shares purchased at each price within the ranges set forth in footnotes 1 and 3 through 5 herein. ( 2 )The shares are beneficially owned by Tang Capital Partners, LP ("TCP"). Kevin Tang is the sole manager of Tang Capital Management, LLC ("TCM"), which is the general partner of TCP. Michael Hearne is the Chief Financial Officer of La Jolla Pharmaceutical Company, as well as Chief Financial Officer of TCM. Mr. Tang and Mr. Hearne each have a pecuniary interest in the shares beneficially held by TCP. ( 3 )The prices reported in Column 4 are weighted-average prices. These shares were purchased in multiple transactions at prices ranging from $3.67 to $3.90. ( 4 )The prices reported in Column 4 are weighted-average prices. These shares were purchased in multiple transactions at prices ranging from $3.73 to $3.89. ( 5 )The prices reported in Column 4 are weighted-average prices. These shares were purchased in multiple transactions at prices ranging from $3.77 to $4.50.

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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