PEGASYSTEMS INC — Major Shareholding Notification 2010

Apr 12, 2010

| UNITED
STATES |
| --- |
| SECURITIES
AND EXCHANGE COMMISSION |
| Washington,
D.C. 20549 |

*SCHEDULE 13G*

*Under the Securities Exchange Act of 1934 (Amendment No. 1)**

*Pegasystems Inc.*

(Name of Issuer)

*Common Stock*

(Title of Class of Securities)

*705573103*

(CUSIP Number)

*March 31, 2010*

(Date of Event Which Requires Filing of this Statement)

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

x	Rule 13d-1(b)
o	Rule 13d-1(c)
o	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. 705573103 — 1. | Names of Reporting Persons Fred Alger Management, Inc. 13-2510833 Alger Associates, Incorporated
13-3017981 | |
| --- | --- | --- |
| 2. | Check the Appropriate Box
if a Member of a Group (See Instructions) | |
| | (a) | o |
| | (b) | x |
| 3. | SEC Use Only | |
| 4. | Citizenship or Place of
Organization New York, New York | |
| Number of Shares Beneficially Owned by Each Reporting Person With | 5. | Sole Voting Power 1,761,883 |
| | 6. | Shared Voting Power -0- |
| | 7. | Sole Dispositive Power 1,761,883 |
| | 8. | Shared Dispositive Power -0- |
| 9. | Aggregate Amount
Beneficially Owned by Each Reporting Person 1,761,883 | |
| 10. | Check if the Aggregate
Amount in Row (9) Excludes Certain Shares (See Instructions) o | |
| 11. | Percent of Class
Represented by Amount in Row (9) 4.79% | |
| 12. | Type of Reporting Person
(See Instructions) Fred Alger Management, Inc. IA Alger Associates, Incorporated
HC | |

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CUSIP No. 705573103
Item 1.
	(a)	Name of Issuer Pegasystems Inc.
	(b)	Address of Issuer’s
Principal Executive Offices 101 Main Street Cambridge, MA 02142
Item 2.
	(a)	Name of Person Filing 1. Fred Alger
Management, Inc.* 2. Alger
Associates, Incorporated
	(b)	Address of Principal
Business Office or, if none, Residence 111 Fifth Avenue, New York, NY 10003
	(c)	Citizenship New York
	(d)	Title of Class of
Securities Common Stock
	(e)	CUSIP Number 36238G102
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)	o	Broker or dealer
registered under section 15 of the Act (15 U.S.C. 78o);
	(b)	o	Bank as defined in section
3(a)(6) of the Act (15 U.S.C. 78c);
	(c)	o	Insurance company as
defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
	(d)	o	Investment company
registered under section 8 of the Investment Company Act of 1940 (15 U.S.C.
80a-8);
	(e)	x	An investment adviser in
accordance with §240.13d-1(b)(1)(ii)(E);
	(f)	o	An employee benefit plan
or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);
	(g)	o	A parent holding company
or control person in accordance with §240.13d-1(b)(1)(ii)(G);
	(h)	o	A savings association as
defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C.
1813);
	(i)	o	A church plan that is
excluded from the definition of an investment company under section 3(c)(14)
of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
	(j)	o	A non-U.S. institution in
accordance with § 240.13d–1(b)(1)(ii)(J);
	(k)	o	Group, in accordance with
§ 240.13d–1(b)(1)(ii)(K). If filing as a non-U.S. institution in accordance
with § 240.13d–1(b)(1)(ii)(J), please specify the type of
institution:____

• By virtue of the Alger family’s ownership of a controlling interest in Alger Associates, which indirectly owns Fred Alger Management, Inc., ownership of the shares may be imputed to the Alger Family.

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CUSIP No. 705573103 — Item 4.	Ownership
Provide the following
information regarding the aggregate number and percentage of the class of
securities of the issuer identified in Item 1.
	(a)	Amount beneficially
owned: 1,761,883
	(b)	Percent of class: 4.79%
	(c)	Number of shares as to
which the person has:
		(i)	Sole power to vote or to
direct the vote 1,761,883
		(ii)	Shared power to vote or to
direct the vote -0-
		(iii)	Sole power to dispose or
to direct the disposition of 1,761,883
		(iv)	Shared power to dispose or
to direct the disposition of -0-
Item 5.	Ownership of Five Percent or Less
of a Class
If this statement is being filed to report the fact
that as of the date hereof the reporting person has ceased to be the
beneficial owner of more than five percent of the class of securities, check
the following x .
Item 6.	Ownership of More than Five Percent
on Behalf of Another Person
n/a
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

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| Item 10. |
| --- |
| (a) The following certification shall be
included if the statement is filed pursuant to s240.13d-1(b): By signing below I
certify that, to the best of my knowledge and belief, the securities referred
to above were acquired and are held in the ordinary course of business and
were not acquired and not held for the purpose of or with the effect of
changing or influencing the control of the issuer of the securities and were
not acquired and are not held in connection with or as a participant in any
transaction having that purpose or effect. |

*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.

FRED ALGER MANAGEMENT, INC.
By:	/s/ Hal Liebes
Executive Vice President
April 12, 2010
ALGER ASSOCIATES, INC.
By:	/s/ Hal Liebes
Director
April 12, 2010

The original statement shall be signed by each person on whose behalf the statement is filed or his authorized representative. If the statement is signed on behalf of a person by his authorized representative other than an executive officer or general partner of the filing person, evidence of the representative’s authority to sign on behalf of such person shall be filed with the statement, provided, however, that a power of attorney for this purpose which is already on file with the Commission may be incorporated by reference. The name and any title of each person who signs the statement shall be typed or printed beneath his signature.

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See s240.13d-7 for other parties for whom copies are to be sent.

ATTENTION. INTENTIONAL MISSTATEMENTS OR OMISSIONS OF FACT CONSTITUTE FEDERAL CRIMINAL VIOLATIONS (SEE 18 U.S.C. 1001).

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