UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No. 17)*

Pegasystems Inc.

(Name of Issuer)

Common Stock, $.01 par value per share

(Title of Class of Securities)

705573 103

(CUSIP Number)

December 31, 2017

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

☐ Rule 13d-1(b)

☐ Rule 13d-1(c)

☒ Rule 13d-1(d)

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

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CUSIP No. 705573 10 3

(1)	Names of reporting persons I.R.S. Identification Nos. of above persons (entities only). Alan Trefler N/A
(2)	Check the appropriate box if a member of a group (see instructions) (a)  ☐        (b)  ☐
(3)	SEC use only
(4)	Citizenship or place of organization United States
Number of shares beneficially owned by each reporting person with:		(5)	Sole voting power 39,843,848
		(6)	Shared voting power 98,000
		(7)	Sole dispositive power 39,843,848
		(8)	Shared dispositive power 98,000
(9)	Aggregate amount beneficially owned by each reporting person 39,941,848
(10)	Check if the aggregate amount in Row (9) excludes certain shares (see instructions) ☐
(11)	Percent of class represented by amount in Row (9) 51.13%
(12)	Type of reporting person (see instructions) IN

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Item 1.

(a) Name of Issuer

Pegasystems Inc.

(b) Address of Issuer’s Principal Executive Offices

1 Rogers Street

Cambridge, MA 02142

Item 2.

(a) Name of Person Filing

Alan Trefler

(b) Address of Principal Business Office or, if none, Residence

The business address of the reporting person is:

c/o Pegasystems Inc.

1 Rogers Street

Cambridge, MA 02142

(c) Citizenship

United States

(d) Title of Class of Securities

Common Stock, $.01 par value per share (the “Common Stock”), of Pegasystems Inc.

(e) CUSIP Number

705573 10 3

Item 3. If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a) Not Applicable.

Item 4. Ownership.

(a) Amount beneficially owned:

39,941,848 shares of Common Stock which includes 98,000 shares held by the Trefler Foundation, of which Mr. Trefler has no pecuniary or beneficial interest, and expressly disclaims beneficial ownership of such shares. Mr. Trefler does however retain voting and dispositive control over such shares.

(b) Percent of class:

51.13% of the outstanding shares of Common Stock. The foregoing percentage was calculated based on the 78,110,800 shares of Common Stock outstanding as of December 31, 2017.

(c) Number of shares as to which the person has:

(i) Sole power to vote or to direct the vote of 39,843,848 shares.

(ii) Shared power to vote or to direct the vote of 98,000 shares.

(iii) Sole power to dispose or to direct the disposition of 39,843,848 shares.

(iv) Shared power to dispose or to direct the disposition of 98,000 shares.

Item 5. Ownership of Five Percent or Less of a Class

N/A

Item 6. Ownership of More than Five Percent on Behalf of Another Person.

N/A

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Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person.

N/A

Item 8. Identification and Classification of Members of the Group

N/A

Item 9. Notice of Dissolution of Group

N/A

Item 10. Certification

N/A

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

February 13, 2018

Date

/S/ ALAN TREFLER

Signature

Alan Trefler

Name/Title

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