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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(AMENDMENT NO. ) *

WebSideStory, Inc.

(Name of Issuer)

Common Stock Par Value $.01

(Title of Class of Securities)

947685 10 3

(CUSIP Number)

12-31-04

(Date of Event Which Requires Filing of this Statement)

THIS SCHEDULE IS BEING FILED PURSUANT TO RULE 13d-1

Check the following box if a fee is being paid with this statement [ ]. (A fee is not required only if the filing person: (1) has a previous statement on file reporting beneficial ownership of more than five percent of the class of securities described in Item 1; and (2) has filed no amendment subsequent thereto reporting beneficial ownership of five percent or less of such class.) (See Rule 13d-7).

*	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. 947685 10 3		13G


1	NAME OF REPORTING PERSON S.S. OR I.R.S IDENTIFICATION NO. OF ABOVE PERSON TA/Advent VIII L.P. Advent Atlantic and Pacific III L.P. TA Executives Fund LLC TA Investors LLC	04-3334380 04-3299318 04-3398534 04-3395404
2	CHECK THE BOX IF A MEMBER OF A GROUP* (a) x (b) ¨
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION TA/Advent VIII L.P. Advent Atlantic and Pacific III L.P. TA Executives Fund LLC TA Investors LLC	Delaware Delaware Delaware Delaware


NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING WITH	5 SOLE VOTING POWER TA/Advent VIII L.P. Advent Atlantic and Pacific III L.P. TA Executives Fund LLC TA Investors LLC	1,743,695 328,101 33,129 34,873
	6 SHARED VOTING POWER N/A
	7 SOLE DISPOSITIVE POWER TA/Advent VIII L.P. Advent Atlantic and Pacific III L.P. TA Executives Fund LLC TA Investors LLC	1,743,695 328,101 33,129 34,873
	8 SHARED DISPOSITIVE POWER N/A


9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON TA/Advent VIII L.P. Advent Atlantic and Pacific III L.P. TA Executives Fund LLC TA Investors LLC	1,743,695 328,101 33,129 34,873
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 TA/Advent VIII L.P. Advent Atlantic and Pacific III L.P. TA Executives Fund LLC TA Investors LLC	11.16% 2.10% 0.21% 0.22%
12	TYPE OF REPORTING PERSON Two Partnerships Two Limited Liability Companies

SEE INSTRUCTION BEFORE FILLING OUT!

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ATTACHMENT TO FORM 13G


ITEM 1 (a)	NAME OF ISSUER: WebSideStory, Inc.

ITEM 1 (b)	ADDRESS OF ISSUER’S PRINCIPAL EXECUTIVE OFFICES:
	10182 Telesis Court San Diego, CA 92121

ITEM 2 (a)	NAME OF PERSON FILING: TA/Advent VIII L.P. Advent Atlantic and Pacific III L.P. TA Executives Fund LLC TA Investors LLC.

ITEM 2 (b)	ADDRESS OF PRINCIPAL BUSINESS OFFICE: c/o TA Associates 125 High Street, Suite 2500 Boston, MA 02110

ITEM 2 (c)	CITIZENSHIP: Not Applicable

ITEM 2 (d)	TITLE AND CLASS OF SECURITIES: Common

ITEM 2 (e)	CUSIP NUMBER: 947685 10 3

ITEM 3	IF THIS STATEMENT IS FILED PURSUANT TO RULES 13d-1 (b) OR 13d-2 (b), CHECK WHETHER THE PERSON FILING IS A: Not Applicable

ITEM 4	OWNERSHIP

ITEM 4 (a)	AMOUNT BENEFICIALLY OWNED:	COMMON STOCK

	TA/Advent VIII L.P. Advent Atlantic and Pacific III L.P. TA Executives Fund LLC TA Investors LLC	1,743,695 328,101 33,129 34,873

ITEM 4 (b)	PERCENT OF CLASS	PERCENTAGE

	TA/Advent VIII L.P. Advent Atlantic and Pacific III L.P TA Executives Fund LLC TA Investors LLC	11.16 2.10 0.21 0.22	% % % %

ITEM 4 (c)	NUMBER OF SHARES AS TO WHICH SUCH PERSON HAS:

	(I) SOLE POWER TO VOTE OR DIRECT THE VOTE:	COMMON STOCK

	TA/Advent VIII L.P. Advent Atlantic and Pacific III L.P TA Executives Fund LLC TA Investors LLC	1,743,695 328,101 33,129 34,873

	(II) SHARED POWER TO VOTE OR DIRECT THE VOTE:	N/A

	(III) SOLE POWER TO DISPOSE OR DIRECT THE DISPOSITION:	COMMON STOCK

	TA/Advent VIII L.P. Advent Atlantic and Pacific III L.P TA Executives Fund LLC TA Investors LLC	1,743,695 328,101 33,129 34,873

	(IV) SHARED POWER TO DISPOSE OR DIRECT THE DISPOSITION	N/A

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ITEM 5		OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS: Not Applicable

ITEM 6		OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON: Not Applicable

ITEM 7		IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY THAT ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY: Not Applicable

ITEM 8		IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP: This schedule 13G is filed pursuant to Rule 13d-l (d). For the agreement of group members to a joint filing, see below.

ITEM 9		NOTICE OF DISSOLUTION OF GROUP: Not Applicable

ITEM 10		CERTIFICATION: Not Applicable

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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.

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AGREEMENT FOR JOINT FILING

TA/Advent VIII L.P., Advent Atlantic and Pacific III L.P., TA Executives Fund LLC and TA Investors LLC, hereby agree that TA Associates shall file with the Securities and Exchange Commission a joint schedule 13G on behalf of the above-named parties concerning their beneficial ownership of WebSideStory, Inc.

Dated: February 2, 2005


TA/ADVENT VIII L.P.

By:		TA Associates VIII LLC, its General Partner

By:		TA Associates, Inc. its Manager

By:		/s/ THOMAS P. ALBER
		Thomas P. Alber, Chief Financial Officer

ADVENT ATLANTIC AND PACIFIC III L.P.

By:		TA Associates AAP III Partners L.P., its General Partner

By:		TA Associates, Inc. its General Partner

By:		/s/ THOMAS P. ALBER
		Thomas P. Alber, Chief Financial Officer

TA EXECUTIVES FUND LLC

By:		TA Associates, Inc., its Manager

By:		/s/ THOMAS P. ALBER
		Thomas P. Alber, Chief Financial Officer

TA INVESTORS LLC

By:		TA Associates. Inc., its Manager

By:		/s/ THOMAS P. ALBER
		Thomas P. Alber, Chief Financial Officer

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TA ADVENT VIII LP SC 13G