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 * Trefler Leon   2. Issuer Name and Ticker or Trading Symbol PEGASYSTEMS INC [PEGA] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) SVP, Global Customer Success (Last) (First) (Middle) C/O PEGASYSTEMS INC., 1 ROGERS STREET 3. Date of Earliest Transaction (Month/Day/Year) 09/04/2018 (Street) CAMBRIDGE, MA 02142 4. If Amendment, Date Original Filed(Month/Day/Year) 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 (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 09/04/2018   M   620 (1) A $ 0 9,889 D   Common Stock 09/04/2018   F   183 D $ 63.7 9,706 D   Common Stock 09/04/2018   M   370 (2) A $ 0 10,076 D   Common Stock 09/04/2018   F   109 D $ 63.7 9,967 D   Common Stock 09/04/2018   S   3,175 D $ 63.05 (3) 6,792 (4) 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

Restricted Stock Units (5)

$ 0

09/04/2018

M

620 (1)

03/02/2016

(6)

Common Stock

620

$ 0

3,716

D

Restricted Stock Units (5)

$ 0

09/04/2018

M

370 (2)

03/02/2018

(6)

Common Stock

370

$ 0

5,171

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Trefler Leon C/O PEGASYSTEMS INC. 1 ROGERS STREET CAMBRIDGE, MA 02142			SVP, Global Customer Success

Signatures

/s/ Janet Mesrobian, Esq., Attorney-In-Fact for Leon Trefler		09/06/2018
**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)	Represents 5% vesting on September 2, 2018, with a release date of September 4, 2018, the first business day following the vesting. The original grant was 12,383 restricted stock units, with 20% vesting on March 2, 2016, and the remaining 80% vesting in equal quarterly installments over the remaining 4 years.
(2)	Represents 5% vesting on September 2, 2018, with a release date of September 4, 2018, the first business day following the vesting. The original grant was 7,387 restricted stock units, with 20% vesting on March 2, 2018, and the remaining 80% vesting in equal quarterly installments over the remaining 4 years.
(3)	Represents the weighted average of the sale prices, ranging from $63.05 to $63.10. The individual has provided the Company, and undertakes to provide to the staff of the Securities and Exchange Commission or any security holder of the Company, upon request, full information regarding the number of shares sold at each separate price.
(4)	Does not include shares of common stock subject to unvested restricted stock units and options awards.
(5)	Each restricted stock unit represents the right to receive, following vesting, one share of the issuer's common stock.
(6)	Once vested, the shares of common stock are not subject to expiration.

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