Sec Form 4 Filing - Schmidt Joan @ ARENA PHARMACEUTICALS INC - 2021-03-15

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 Schmidt Joan 2. Issuer Name and Ticker or Trading Symbol ARENA PHARMACEUTICALS INC [ ARNA] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) EVP, General Counsel & Sec (Last) (First) (Middle) C/O ARENA PHARMACEUTICALS, INC., 6154 NANCY RIDGE DRIVE 3. Date of Earliest Transaction (MM/DD/YY) 03/15/2021 (Street) SAN DIEGO, CA92121 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 03/15/2021 M 12,600 ( 1 ) A $ 0 19,475 D Common Stock 03/15/2021 F 4,874 ( 2 ) D $ 77.58 14,601 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 Performance Restricted Stock Unit ( 1 ) 03/15/2021 M 12,600 ( 1 ) ( 1 ) 01/03/2022 Common Stock 12,600 ( 3 ) $ 0 0 ( 1 ) D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Schmidt Joan C/O ARENA PHARMACEUTICALS, INC. 6154 NANCY RIDGE DRIVE SAN DIEGO, CA92121 EVP, General Counsel & Sec Signatures /s/ Andrew J. Cronauer, as Attorney-in-Fact 04/02/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On March 15, 2020, the Reporting Person was granted 6,300 target Performance Restricted Stock Units ("2020 PRSUs"). The 2020 PRSUs represented a contingent right to receive a number of shares of Arena's common stock equal to 0%, 100%, or 200% of the target amount. Such common shares would vest, if at all, upon Arena's common stock reaching certain Nasdaq "Closing Price" thresholds during the performance period from the grant date through Jan. 3, 2022 (the "Performance Period") and satisfaction of a subsequent continuing service requirement. The 2020 PRSUs also contained a 1-year minimum vesting period. The Closing Price targets were met during 2020 and the continuing service requirements were subsequently satisfied. Therefore, upon the conclusion of the 1-year minimum vesting period, all shares shares issuable pursuant to the 2020 PRSUs (200% of the target amount) vested and released as reported herein. ( 2 )Represents the number of shares withheld by, and surrendered to, Arena relating to tax withholding in connection with the issuance of shares under the 2020 PRSUs. ( 3 )The amount reported in Column 7 of Table II represents the common shares that vested. The 2020 PRSUs have now fully vested and no common shares remain issuable thereunder.

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