Ownership Submission
FORM 3
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF 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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(Print or Type Responses)
1. Name and Address of Reporting Person *
  TA ADVENT VIII LP
2. Date of Event Requiring Statement (Month/Day/Year)
12/12/2006
3. Issuer Name and Ticker or Trading Symbol
IPG PHOTONICS CORP [IPGP]
(Last)
(First)
(Middle)
JOHN HANCOCK TOWER, 200 CLARENDON ST, 56TH FLOOR
4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

BOSTON, MA 02116
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 Beneficially Owned
1.Title of Security
(Instr. 4)
2. Amount of Securities Beneficially Owned
(Instr. 4)
3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)
4. Nature of Indirect Beneficial Ownership
(Instr. 5)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)
2. Date Exercisable and Expiration Date
(Month/Day/Year)
3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)
4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)
6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Series B Preferred Stock 12/12/2006   (3) Common Stock 354,767 $ (1) D  
Series B Warrants 12/12/2006 04/01/2008 Common Stock (2) $ (2) D  

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
TA ADVENT VIII LP
JOHN HANCOCK TOWER
200 CLARENDON ST, 56TH FLOOR
BOSTON, MA 02116
  X      

Signatures

TA/Advent VIII L.P. 12/12/2006
**Signature of Reporting Person Date

By: TA Associates VIII LLC, its General Partner 12/12/2006
**Signature of Reporting Person Date

By: TA Associates, Inc., its Manager 12/12/2006
**Signature of Reporting Person Date

By: Thomas P. Alber, Chief Financial Officer 12/12/2006
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(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) The number of shares of Common Stock is subject to adjustment based upon the initial public offering price in connection with the issuer's initial public offering.
(2) The number of shares of Common Stock underlying the warrants is indeterminate and will be determined based upon the initial public offering price of the Common Stock in connection with the issuer's initial public offering.
(3) N/A
 
Remarks:
The Reporting Person has a representative on the issuer's board of directors.  Michael Child currently serves as the Reporting Person's representative on the board of directors and the Reporting Person is deemed a director of the issuer by deputization.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, See Instruction 6 for procedure.

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.