<PAGE>   1
    As filed with the Securities and Exchange Commission on December 19, 1997

                                                Registration No. 333-___________

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                        INVESTMENT TECHNOLOGY GROUP, INC.
             (Exact Name of Registrant as Specified in Its Charter)

                                    DELAWARE
         (State or Other Jurisdiction of Incorporation or Organization)

                                   13-3757717
                      (I.R.S. Employer Identification No.)

         380 Madison Avenue
              4th Floor
             New York, NY                                               10017
(Address of Principal Executive Offices)                              (Zip Code)

         INVESTMENT TECHNOLOGY GROUP, INC. EMPLOYEE STOCK PURCHASE PLAN
                            (Full Title of the Plan)

                               TIMOTHY H. HOSKING
              Senior Vice President, General Counsel and Secretary
                        Investment Technology Group, Inc.
                               380 Madison Avenue
                                    4th Floor
                               New York, NY 10017
                     (Name and Address of Agent For Service)

                                 (212) 444-6363
          (Telephone Number, Including Area code, of Agent For Service)

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
      Title Of             Amount           Proposed Maximum      Proposed Maximum
  Securities To Be          To Be            Offering Price      Aggregate Offering         Amount Of
   Registered (1)        Registered (1)        Per Share               Price            Registration Fee
   --------------        --------------        ---------               -----            ----------------
<S>                      <C>                <C>                  <C>                    <C>
Common Stock, $.01
par value                   250,000             $30.25 (2)           $7,562,500           $2,230.94 (3)
</TABLE>

(1)      This registration statement (the "Registration Statement") covers
         shares of Common Stock, $.01 par value, of Investment Technology Group,
         Inc. (the "Company") which may be offered and sold from time to time
         pursuant to the Company's Employee Stock Purchase Plan (the "Plan").
         Pursuant to Rule 416(a), the number of shares being registered shall be
         adjusted to include any additional shares which may become issuable as
         a result of stock splits, stock dividends or similar transactions in
         accordance with the anti-dilution provisions of the Plan.

(2)      Estimated pursuant to paragraphs (c) and (h) of Rule 457 solely for the
         purpose of calculating the registration fee, based upon the average of
         the reported high and low sales prices for shares of Common Stock on
         December 18, 1997, as reported in the Nasdaq National Market.

(3)      Calculated pursuant to Section 6(b) of the Securities Act of 1933, as
         amended, as follows: $295 per $1,000,000 of proposed maximum aggregate
         offering price.
<PAGE>   2
                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

         ITEM 1.  PLAN INFORMATION.

                  Omitted as permitted pursuant to Rule 428 and Form S-8.


         ITEM 2.  REGISTRANT INFORMATION AND EMPLOYEE PLAN ANNUAL INFORMATION.

                  Omitted as permitted pursuant to Rule 428 and Form S-8.


                                      I-1
<PAGE>   3
                                     PART II

                      INFORMATION REQUIRED IN REGISTRATION
                                    STATEMENT


ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

         The following documents of Investment Technology Group, Inc., a
Delaware corporation (the "Company"), filed with the Securities and Exchange
Commission (the "Commission"), are incorporated by reference into this
Registration Statement:

         (a) The Company's Annual Report on Form 10-K for the Company's fiscal
year ended December 31, 1996, filed pursuant to Section 13(a) of the Securities
Exchange Act of 1934, as amended (the "Exchange Act").

         (b) The Company's Quarterly Reports on Form 10-Q for the Company's
fiscal quarters ended March 28, 1997, June 27, 1997, and September 26, 1997,
filed pursuant to Section 13(a) of the Exchange Act.

         (c) The description of the Common Stock of the Company contained in the
Company's Registration Statement on Form S-1 (Registration Number 33-76474,
filed with the Commission on March 15, 1994), incorporated by reference in the
Company's Form 8-A (filed with the Commission on March 16, 1994), including any
other amendment or report filed for the purpose of updating such description.

         All reports and other documents subsequently filed by the Company
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act prior to the
filing of a post-effective amendment which indicates that all securities offered
have been sold or which deregisters all securities then remaining unsold shall
be deemed to be incorporated by reference in this Registration Statement and to
be a part hereof from the date of filing of such documents.

         Any statement contained in a document incorporated or deemed to be
incorporated in this Registration Statement by reference shall be deemed to be
modified or superseded for purposes of this Registration Statement to the extent
that a statement contained in this Registration Statement or in any other
subsequently filed document which also is or is deemed to be incorporated in
this Registration Statement by reference modifies or supersedes such statement.
Any statement so modified shall not be deemed in its unmodified form, and any
statement so superseded shall not be deemed, to constitute a part of this
Registration Statement.


ITEM 4.  DESCRIPTION OF SECURITIES.

                  Not applicable.


ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

                  Not applicable.


                                      II-1
<PAGE>   4
ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

         The Company's By-laws provide that the Company shall, to the fullest
extent permitted by Section 145 of the Delaware General Corporation Law, as
amended from time to time, indemnify all persons whom it may indemnify pursuant
thereto.

         Under Section 145 of the Delaware General Corporation Law, a
corporation may indemnify any person who was or is a party or is threatened to
be made a party to any threatened, pending or completed action, suit or
proceeding, whether civil, criminal, administrative or investigative (other than
an action by or in the right of the corporation) by reason of the fact that he
or she is or was a director, officer, employee or agent of the corporation, or
is or was serving at the request of the corporation as a director, officer,
employee or agent of another corporation, partnership, joint venture, trust or
other enterprise, against expenses (including attorneys' fees), judgments, fines
and amounts paid in settlement actually and reasonably incurred by such person
in connection with such action, suit or proceeding (i) if such person acted in
good faith and in a manner that person reasonably believed to be in or not
opposed to the best interests of the corporation and (ii), with respect to any
criminal action or proceeding, if he or she had no reasonable cause to believe
such conduct was unlawful. In actions brought by or in the right of the
corporation, a corporation may indemnify such person against expenses (including
attorneys' fees) actually and reasonably incurred by such person in connection
with the defense or settlement of such action or suit if such person acted in
good faith and in a manner which that person reasonably believed to be in or not
opposed to the best interests of the corporation, except that no indemnification
shall be made in respect of any claim, issue or matter as to which that person
shall have been adjudged to be liable to the corporation unless and only to the
extent that the Court of Chancery of the State of Delaware or the court in which
such action or suit was brought shall determine upon application that, despite
the adjudication of liability but in view of all the circumstances of the case,
such person is fairly and reasonably entitled to indemnification for such
expenses which the Court of Chancery or other such court shall deem proper. To
the extent that such person has been successful on the merits or otherwise in
defending any such action, suit or proceeding referred to above or any claim,
issue or matter therein, he or she is entitled to indemnification for expenses
(including attorneys' fees) actually and reasonably incurred by such person in
connection therewith. Expenses (including attorneys' fees) incurred by an
officer or director in defending any civil, criminal, administrative or
investigative action, suit or proceeding may be paid by the corporation in
advance of the final disposition of such action, suit or proceeding upon receipt
of an undertaking by or on behalf of such director or officer to repay such
amount if it is ultimately determined that he is not entitled to be indemnified
by the corporation as authorized in Section 145. Such expenses (including
attorneys' fees) incurred by other employees and agents may be so paid upon such
terms and conditions, if any, as the board of directors deems appropriate. The
indemnification and advancement of expenses provided for, or granted pursuant
to, Section 145 is not exclusive of any other rights of indemnification or
advancement of expenses to which those seeking indemnification or advancement of
expenses may be entitled, and a corporation may purchase and maintain insurance
against liabilities asserted against any former or current director, officer,
employee or agent of the corporation, or a person who is or was serving at the
request of the corporation as a director, officer, employee or agent of another
corporation, partnership, joint venture, trust or other enterprise whether or
not the power to indemnify is provided by the statute.

         Article Seven of the Company's Certificate of Incorporation provides
that the Company's directors will not be personally liable to the Company or its
stockholders for monetary damages resulting from breaches of their fiduciary
duty as directors except (i) for any breach of the duty of loyalty to the
Company or its stockholders, (ii) for acts or omissions not in good faith or
which involve intentional misconduct or a knowing violation of law, (iii) under
Section 174 of the Delaware General Corporation Law (involving certain unlawful
dividends or stock


                                      II-2
<PAGE>   5
repurchases) or (iv) for any transaction from which the director derived an
improper personal benefit.

         The Company's directors and officers are covered by insurance policies
insuring against certain civil liabilities, including liabilities under the
federal securities laws, which might be incurred by them in such capacity.


ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

                  Not applicable.

ITEM 8.  EXHIBITS.

         4(a)     Certificate of Incorporation of the Company (incorporated by
                  reference to Exhibit 3.1 to the Company's Registration
                  Statement on Form S-1, Number 33-76474, filed with the
                  Commission on March 15, 1994 (the "Form S-1 Registration
                  Statement")).

         4(b)     By-laws of the Company (incorporated by reference to Exhibit
                  3.2 to the Form S-1 Registration Statement, filed with the
                  Commission on March 15, 1994).

         5        Opinion of Steven C. Root, Esq., with respect to the legality
                  of securities being registered.

         23(a)    Consent of KPMG Peat Marwick LLP.

         23(b)    Consent of Steven C. Root, Esq. (included in Exhibit 5).

         24       Powers of Attorney (included on the signature pages of this
                  Part II).


ITEM 9.  UNDERTAKINGS.

                  (a) The undersigned registrant hereby undertakes:

                           (1) To file, during any period in which offers or
         sales are being made, a post-effective amendment to this Registration
         Statement:

                  (i) To include any prospectus required by Section 10(a)(3) of
         the Securities Act of 1933;

                  (ii) To reflect in the Prospectus any facts or events arising
         after the effective date of this Registration Statement (or the most
         recent post-effective amendment thereof) which, individually or in the
         aggregate, represent a fundamental change in the information set forth
         in the Registration Statement; notwithstanding the foregoing, any
         increase or decrease in the volume of securities offered (if the total
         dollar value of securities offered would not exceed that which was
         registered) and any deviation from the low or high end of the estimated
         maximum offering range may be reflected in the form of prospectus filed
         with the Commission pursuant to Rule 424(b) if, in the aggregate, the
         changes in volume and price represent no more than a 20% change in the
         maximum aggregate offering price set forth in the "Calculation of
         Registration Fee" table in the effective registration statement.


                                      II-3
<PAGE>   6
                  (iii) To include any material information with respect to the
         plan of distribution not previously disclosed in this Registration
         Statement or any material change to such information in the
         Registration Statement;

         provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not
         apply if this Registration Statement is on Form S-3 or Form S-8, and
         the information required to be included in a post-effective amendment
         by those paragraphs is contained in periodic reports filed by the
         registrant pursuant to Section 13 or Section 15(d) of the Securities
         Exchange Act of 1934 that are incorporated by reference in this
         Registration Statement.

                           (2) That, for the purpose of determining any
         liability under the Securities Act of 1933, each such post-effective
         amendment shall be deemed to be a new registration statement relating
         to the securities offered therein, and the offering of such securities
         at that time shall be deemed to be the initial bona fide offering
         thereof.

                           (3) To remove from registration by means of a
         post-effective amendment any of the securities being registered which
         remain unsold at the termination of the offering.

                  (b) The undersigned registrant hereby undertakes that, for
         purposes of determining any liability under the Securities Act of 1933,
         each filing of the registrant's annual report pursuant to Section 13(a)
         or Section 15(d) of the Securities Exchange Act of 1934 (and, where
         applicable, each filing of an employee benefit plan's annual report
         pursuant to Section 15(d) of the Securities Exchange Act of 1934) that
         is incorporated by reference in the Registration Statement shall be
         deemed to be a new registration statement relating to the securities
         offered therein, and the offering of such securities at that time shall
         be deemed to be the initial bona fide offering thereof.

                  (c) Insofar as indemnification for liabilities arising under
         the Securities Act of 1933 may be permitted to directors, officers and
         controlling persons of the registrant pursuant to the foregoing
         provisions, or otherwise, the registrant has been advised that in the
         opinion of the Securities and Exchange Commission such indemnification
         is against public policy as expressed in the Act and is, therefore,
         unenforceable. In the event that a claim for indemnification against
         such liabilities (other than the payment by the registrant of expenses
         incurred or paid by a director, officer or controlling person of the
         registrant in the successful defense of any action, suit or proceeding)
         is asserted by such director, officer or controlling person in
         connection with the securities being registered, the registrant will,
         unless in the opinion of its counsel the matter has been settled by
         controlling precedent, submit to a court of appropriate jurisdiction
         the question whether such indemnification by it is against public
         policy as expressed in the Act and will be governed by the final
         adjudication of such issue.


                                      II-4
<PAGE>   7
                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of New York, State of New York, on the 19th day of
December, 1997.

                                    INVESTMENT TECHNOLOGY GROUP, INC.



                                    By: /s/ SCOTT P. MASON
                                       -------------------------------------
                                                  Scott P. Mason
                                       President and Chief Executive Officer

         Each person whose signature appears below constitutes and appoints
Scott P. Mason, President and Chief Executive Officer of the Company, and
Timothy H. Hosking, Senior Vice President, General Counsel and Secretary of the
Company, and each of them, his true and lawful attorney-in-fact and agent, with
full power of substitution and resubstitution, for him and in his name, place
and stead, in any and all capacities, to sign any and all amendments (including
post-effective amendments) to this Registration Statement and any and all other
documents and instruments incidental thereto, and to file the same, with all
exhibits thereto, and all documents in connection therewith, with the Securities
and Exchange Commission and any other regulatory authority, granting unto said
attorney-in-fact and agent, or his substitute, full power and authority to do
and perform each and every act and thing requisite and necessary to be done, as
fully to all intents and purposes as he might or could do in person, hereby
ratifying and confirming all that said attorney-in-fact and agent, or his
substitute, may lawfully do or cause to be done by virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities and on the dates indicated.

<TABLE>
<CAPTION>
         SIGNATURE                                    POSITION                            DATE
<S>                                          <C>                                 <C> 
/s/      SCOTT P. MASON                      Director, President and Chief       December 19, 1997
-------------------------------------        Executive Officer
         Scott P. Mason                      (Principal Executive Officer)


/s/      JOHN R. MACDONALD                   Senior Vice President and           December 19, 1997
-------------------------------------        Chief Financial Officer
         John R. MacDonald                   (Principal Financial Officer and
                                             Principal Accounting Officer)

/s/      RAYMOND L. KILLIAN, JR.             Chairman of the Board and           December 19, 1997
-------------------------------------        Director
         Raymond L. Killian, Jr.     
</TABLE>


                                      II-5
<PAGE>   8
<TABLE>
<CAPTION>
         SIGNATURE                                    POSITION                            DATE
<S>                                          <C>                                 <C> 

/s/      FRANK E. BAXTER                     Director                            December 19, 1997
-------------------------------------
         Frank E. Baxter

/s/      RICHARD G. DOOLEY                   Director                            December 19, 1997
-------------------------------------
         Richard G. Dooley

/s/      WILLIAM I. JACOBS                   Director                            December 19, 1997
-------------------------------------
         William I. Jacobs

/s/      ROBERT L. KING                      Director                            December 19, 1997
-------------------------------------
         Robert L. King

/s/      MICHAEL L. KLOWDEN                  Director                            December 19, 1997
-------------------------------------
         Michael L. Klowden

/s/      DALE A. PROUTY                      Director                            December 19, 1997
-------------------------------------
         Dale A. Prouty

/s/      MARK A. WOLFSON                     Director                            December 19, 1997
-------------------------------------
         Mark A. Wolfson
</TABLE>


                                      II-6
<PAGE>   9
                                  EXHIBIT INDEX

Exhibit
Number            Description

4(a)     Certificate of Incorporation of the Company (incorporated by reference
         to Exhibit 3.1 to the Company's Registration Statement on Form S-1,
         Number 33-76474, filed with the Commission on March 15, 1994 (the "Form
         S-1 Registration Statement")).

4(b)     By-laws of the Company (incorporated by reference to Exhibit 3.2 to the
         Form S-1 Registration Statement, filed with the Commission on March 15,
         1994).

5        Opinion of Steven C. Root, Esq., with respect to the legality of
         securities being registered.

23(a)    Consent of KPMG Peat Marwick LLP.

23(b)    Consent of Steven C. Root, Esq. (included in Exhibit 5).

24       Powers of Attorney (included on the signature pages of Part II of the
         Registration Statement).
[{"type": "S-8", "sequence": "1", "description": "INVESTMENT TECHNOLOGY GROUP, INC.", "secsgml_size_bytes": 22972}]
{"company-data": {"conformed-name": "INVESTMENT TECHNOLOGY GROUP INC", "cik": "0000920424", "assigned-sic": "6211", "irs-number": "133757717", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-42725", "film-number": "97741370"}, "business-address": {"street1": "380 MADISON AVE", "city": "NEW YORK", "state": "NY", "zip": "10017", "phone": "2125884000"}, "mail-address": {"street1": "11100 SANTA MONICA BLVD", "street2": "12TH FLOOR", "city": "LOS ANGELES", "state": "CA", "zip": "90025"}}
1
    As filed with the Securities and Exchange Commission on December 19, 1997

                                                Registration No. 333-___________

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                        INVESTMENT TECHNOLOGY GROUP, INC.
             (Exact Name of Registrant as Specified in Its Charter)

                                    DELAWARE
         (State or Other Jurisdiction of Incorporation or Organization)

                                   13-3757717
                      (I.R.S. Employer Identification No.)

         380 Madison Avenue
              4th Floor
             New York, NY                                               10017
(Address of Principal Executive Offices)                              (Zip Code)

         INVESTMENT TECHNOLOGY GROUP, INC. EMPLOYEE STOCK PURCHASE PLAN
                            (Full Title of the Plan)

                               TIMOTHY H. HOSKING
              Senior Vice President, General Counsel and Secretary
                        Investment Technology Group, Inc.
                               380 Madison Avenue
                                    4th Floor
                               New York, NY 10017
                     (Name and Address of Agent For Service)

                                 (212) 444-6363
          (Telephone Number, Including Area code, of Agent For Service)

                         CALCULATION OF REGISTRATION FEE
Title Of             Amount           Proposed Maximum      Proposed Maximum
  Securities To Be          To Be            Offering Price      Aggregate Offering         Amount Of
   Registered (1)        Registered (1)        Per Share               Price            Registration Fee
   --------------        --------------        ---------               -----            ----------------
Common Stock, $.01
par value                   250,000             $30.25 (2)           $7,562,500           $2,230.94 (3)
(1)      This registration statement (the "Registration Statement") covers
         shares of Common Stock, $.01 par value, of Investment Technology Group,
         Inc. (the "Company") which may be offered and sold from time to time
         pursuant to the Company's Employee Stock Purchase Plan (the "Plan").
         Pursuant to Rule 416(a), the number of shares being registered shall be
         adjusted to include any additional shares which may become issuable as
         a result of stock splits, stock dividends or similar transactions in
         accordance with the anti-dilution provisions of the Plan.

(2)      Estimated pursuant to paragraphs (c) and (h) of Rule 457 solely for the
         purpose of calculating the registration fee, based upon the average of
         the reported high and low sales prices for shares of Common Stock on
         December 18, 1997, as reported in the Nasdaq National Market.

(3)      Calculated pursuant to Section 6(b) of the Securities Act of 1933, as
         amended, as follows: $295 per $1,000,000 of proposed maximum aggregate
         offering price.
2
                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

         ITEM 1.  PLAN INFORMATION.

                  Omitted as permitted pursuant to Rule 428 and Form S-8.

         ITEM 2.  REGISTRANT INFORMATION AND EMPLOYEE PLAN ANNUAL INFORMATION.

                  Omitted as permitted pursuant to Rule 428 and Form S-8.

                                      I-1
3
                                     PART II

                      INFORMATION REQUIRED IN REGISTRATION
                                    STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

         The following documents of Investment Technology Group, Inc., a
Delaware corporation (the "Company"), filed with the Securities and Exchange
Commission (the "Commission"), are incorporated by reference into this
Registration Statement:

         (a) The Company's Annual Report on Form 10-K for the Company's fiscal
year ended December 31, 1996, filed pursuant to Section 13(a) of the Securities
Exchange Act of 1934, as amended (the "Exchange Act").

         (b) The Company's Quarterly Reports on Form 10-Q for the Company's
fiscal quarters ended March 28, 1997, June 27, 1997, and September 26, 1997,
filed pursuant to Section 13(a) of the Exchange Act.

         (c) The description of the Common Stock of the Company contained in the
Company's Registration Statement on Form S-1 (Registration Number 33-76474,
filed with the Commission on March 15, 1994), incorporated by reference in the
Company's Form 8-A (filed with the Commission on March 16, 1994), including any
other amendment or report filed for the purpose of updating such description.

         All reports and other documents subsequently filed by the Company
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act prior to the
filing of a post-effective amendment which indicates that all securities offered
have been sold or which deregisters all securities then remaining unsold shall
be deemed to be incorporated by reference in this Registration Statement and to
be a part hereof from the date of filing of such documents.

         Any statement contained in a document incorporated or deemed to be
incorporated in this Registration Statement by reference shall be deemed to be
modified or superseded for purposes of this Registration Statement to the extent
that a statement contained in this Registration Statement or in any other
subsequently filed document which also is or is deemed to be incorporated in
this Registration Statement by reference modifies or supersedes such statement.
Any statement so modified shall not be deemed in its unmodified form, and any
statement so superseded shall not be deemed, to constitute a part of this
Registration Statement.

ITEM 4.  DESCRIPTION OF SECURITIES.

                  Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

                  Not applicable.

                                      II-1
4
ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

         The Company's By-laws provide that the Company shall, to the fullest
extent permitted by Section 145 of the Delaware General Corporation Law, as
amended from time to time, indemnify all persons whom it may indemnify pursuant
thereto.

         Under Section 145 of the Delaware General Corporation Law, a
corporation may indemnify any person who was or is a party or is threatened to
be made a party to any threatened, pending or completed action, suit or
proceeding, whether civil, criminal, administrative or investigative (other than
an action by or in the right of the corporation) by reason of the fact that he
or she is or was a director, officer, employee or agent of the corporation, or
is or was serving at the request of the corporation as a director, officer,
employee or agent of another corporation, partnership, joint venture, trust or
other enterprise, against expenses (including attorneys' fees), judgments, fines
and amounts paid in settlement actually and reasonably incurred by such person
in connection with such action, suit or proceeding (i) if such person acted in
good faith and in a manner that person reasonably believed to be in or not
opposed to the best interests of the corporation and (ii), with respect to any
criminal action or proceeding, if he or she had no reasonable cause to believe
such conduct was unlawful. In actions brought by or in the right of the
corporation, a corporation may indemnify such person against expenses (including
attorneys' fees) actually and reasonably incurred by such person in connection
with the defense or settlement of such action or suit if such person acted in
good faith and in a manner which that person reasonably believed to be in or not
opposed to the best interests of the corporation, except that no indemnification
shall be made in respect of any claim, issue or matter as to which that person
shall have been adjudged to be liable to the corporation unless and only to the
extent that the Court of Chancery of the State of Delaware or the court in which
such action or suit was brought shall determine upon application that, despite
the adjudication of liability but in view of all the circumstances of the case,
such person is fairly and reasonably entitled to indemnification for such
expenses which the Court of Chancery or other such court shall deem proper. To
the extent that such person has been successful on the merits or otherwise in
defending any such action, suit or proceeding referred to above or any claim,
issue or matter therein, he or she is entitled to indemnification for expenses
(including attorneys' fees) actually and reasonably incurred by such person in
connection therewith. Expenses (including attorneys' fees) incurred by an
officer or director in defending any civil, criminal, administrative or
investigative action, suit or proceeding may be paid by the corporation in
advance of the final disposition of such action, suit or proceeding upon receipt
of an undertaking by or on behalf of such director or officer to repay such
amount if it is ultimately determined that he is not entitled to be indemnified
by the corporation as authorized in Section 145. Such expenses (including
attorneys' fees) incurred by other employees and agents may be so paid upon such
terms and conditions, if any, as the board of directors deems appropriate. The
indemnification and advancement of expenses provided for, or granted pursuant
to, Section 145 is not exclusive of any other rights of indemnification or
advancement of expenses to which those seeking indemnification or advancement of
expenses may be entitled, and a corporation may purchase and maintain insurance
against liabilities asserted against any former or current director, officer,
employee or agent of the corporation, or a person who is or was serving at the
request of the corporation as a director, officer, employee or agent of another
corporation, partnership, joint venture, trust or other enterprise whether or
not the power to indemnify is provided by the statute.

         Article Seven of the Company's Certificate of Incorporation provides
that the Company's directors will not be personally liable to the Company or its
stockholders for monetary damages resulting from breaches of their fiduciary
duty as directors except (i) for any breach of the duty of loyalty to the
Company or its stockholders, (ii) for acts or omissions not in good faith or
which involve intentional misconduct or a knowing violation of law, (iii) under
Section 174 of the Delaware General Corporation Law (involving certain unlawful
dividends or stock

                                      II-2
5
repurchases) or (iv) for any transaction from which the director derived an
improper personal benefit.

         The Company's directors and officers are covered by insurance policies
insuring against certain civil liabilities, including liabilities under the
federal securities laws, which might be incurred by them in such capacity.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

                  Not applicable.

ITEM 8.  EXHIBITS.

         4(a)     Certificate of Incorporation of the Company (incorporated by
                  reference to Exhibit 3.1 to the Company's Registration
                  Statement on Form S-1, Number 33-76474, filed with the
                  Commission on March 15, 1994 (the "Form S-1 Registration
                  Statement")).

         4(b)     By-laws of the Company (incorporated by reference to Exhibit
                  3.2 to the Form S-1 Registration Statement, filed with the
                  Commission on March 15, 1994).

         5        Opinion of Steven C. Root, Esq., with respect to the legality
                  of securities being registered.

         23(a)    Consent of KPMG Peat Marwick LLP.

         23(b)    Consent of Steven C. Root, Esq. (included in Exhibit 5).

         24       Powers of Attorney (included on the signature pages of this
                  Part II).

ITEM 9.  UNDERTAKINGS.

                  (a) The undersigned registrant hereby undertakes:

                           (1) To file, during any period in which offers or
         sales are being made, a post-effective amendment to this Registration
         Statement:

                  (i) To include any prospectus required by Section 10(a)(3) of
         the Securities Act of 1933;

                  (ii) To reflect in the Prospectus any facts or events arising
         after the effective date of this Registration Statement (or the most
         recent post-effective amendment thereof) which, individually or in the
         aggregate, represent a fundamental change in the information set forth
         in the Registration Statement; notwithstanding the foregoing, any
         increase or decrease in the volume of securities offered (if the total
         dollar value of securities offered would not exceed that which was
         registered) and any deviation from the low or high end of the estimated
         maximum offering range may be reflected in the form of prospectus filed
         with the Commission pursuant to Rule 424(b) if, in the aggregate, the
         changes in volume and price represent no more than a 20% change in the
         maximum aggregate offering price set forth in the "Calculation of
         Registration Fee" table in the effective registration statement.

                                      II-3
6
                  (iii) To include any material information with respect to the
         plan of distribution not previously disclosed in this Registration
         Statement or any material change to such information in the
         Registration Statement;

         provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not
         apply if this Registration Statement is on Form S-3 or Form S-8, and
         the information required to be included in a post-effective amendment
         by those paragraphs is contained in periodic reports filed by the
         registrant pursuant to Section 13 or Section 15(d) of the Securities
         Exchange Act of 1934 that are incorporated by reference in this
         Registration Statement.

                           (2) That, for the purpose of determining any
         liability under the Securities Act of 1933, each such post-effective
         amendment shall be deemed to be a new registration statement relating
         to the securities offered therein, and the offering of such securities
         at that time shall be deemed to be the initial bona fide offering
         thereof.

                           (3) To remove from registration by means of a
         post-effective amendment any of the securities being registered which
         remain unsold at the termination of the offering.

                  (b) The undersigned registrant hereby undertakes that, for
         purposes of determining any liability under the Securities Act of 1933,
         each filing of the registrant's annual report pursuant to Section 13(a)
         or Section 15(d) of the Securities Exchange Act of 1934 (and, where
         applicable, each filing of an employee benefit plan's annual report
         pursuant to Section 15(d) of the Securities Exchange Act of 1934) that
         is incorporated by reference in the Registration Statement shall be
         deemed to be a new registration statement relating to the securities
         offered therein, and the offering of such securities at that time shall
         be deemed to be the initial bona fide offering thereof.

                  (c) Insofar as indemnification for liabilities arising under
         the Securities Act of 1933 may be permitted to directors, officers and
         controlling persons of the registrant pursuant to the foregoing
         provisions, or otherwise, the registrant has been advised that in the
         opinion of the Securities and Exchange Commission such indemnification
         is against public policy as expressed in the Act and is, therefore,
         unenforceable. In the event that a claim for indemnification against
         such liabilities (other than the payment by the registrant of expenses
         incurred or paid by a director, officer or controlling person of the
         registrant in the successful defense of any action, suit or proceeding)
         is asserted by such director, officer or controlling person in
         connection with the securities being registered, the registrant will,
         unless in the opinion of its counsel the matter has been settled by
         controlling precedent, submit to a court of appropriate jurisdiction
         the question whether such indemnification by it is against public
         policy as expressed in the Act and will be governed by the final
         adjudication of such issue.

                                      II-4
7
                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of New York, State of New York, on the 19th day of
December, 1997.

                                    INVESTMENT TECHNOLOGY GROUP, INC.

                                    By: /s/ SCOTT P. MASON
                                       -------------------------------------
                                                  Scott P. Mason
                                       President and Chief Executive Officer

         Each person whose signature appears below constitutes and appoints
Scott P. Mason, President and Chief Executive Officer of the Company, and
Timothy H. Hosking, Senior Vice President, General Counsel and Secretary of the
Company, and each of them, his true and lawful attorney-in-fact and agent, with
full power of substitution and resubstitution, for him and in his name, place
and stead, in any and all capacities, to sign any and all amendments (including
post-effective amendments) to this Registration Statement and any and all other
documents and instruments incidental thereto, and to file the same, with all
exhibits thereto, and all documents in connection therewith, with the Securities
and Exchange Commission and any other regulatory authority, granting unto said
attorney-in-fact and agent, or his substitute, full power and authority to do
and perform each and every act and thing requisite and necessary to be done, as
fully to all intents and purposes as he might or could do in person, hereby
ratifying and confirming all that said attorney-in-fact and agent, or his
substitute, may lawfully do or cause to be done by virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities and on the dates indicated.
SIGNATURE                                    POSITION                            DATE
/s/      SCOTT P. MASON                      Director, President and Chief       December 19, 1997
-------------------------------------        Executive Officer
         Scott P. Mason                      (Principal Executive Officer)

/s/      JOHN R. MACDONALD                   Senior Vice President and           December 19, 1997
-------------------------------------        Chief Financial Officer
         John R. MacDonald                   (Principal Financial Officer and
                                             Principal Accounting Officer)

/s/      RAYMOND L. KILLIAN, JR.             Chairman of the Board and           December 19, 1997
-------------------------------------        Director
         Raymond L. Killian, Jr.
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SIGNATURE                                    POSITION                            DATE
/s/      FRANK E. BAXTER                     Director                            December 19, 1997
-------------------------------------
         Frank E. Baxter

/s/      RICHARD G. DOOLEY                   Director                            December 19, 1997
-------------------------------------
         Richard G. Dooley

/s/      WILLIAM I. JACOBS                   Director                            December 19, 1997
-------------------------------------
         William I. Jacobs

/s/      ROBERT L. KING                      Director                            December 19, 1997
-------------------------------------
         Robert L. King

/s/      MICHAEL L. KLOWDEN                  Director                            December 19, 1997
-------------------------------------
         Michael L. Klowden

/s/      DALE A. PROUTY                      Director                            December 19, 1997
-------------------------------------
         Dale A. Prouty

/s/      MARK A. WOLFSON                     Director                            December 19, 1997
-------------------------------------
         Mark A. Wolfson
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                                  EXHIBIT INDEX

Exhibit
Number            Description

4(a)     Certificate of Incorporation of the Company (incorporated by reference
         to Exhibit 3.1 to the Company's Registration Statement on Form S-1,
         Number 33-76474, filed with the Commission on March 15, 1994 (the "Form
         S-1 Registration Statement")).

4(b)     By-laws of the Company (incorporated by reference to Exhibit 3.2 to the
         Form S-1 Registration Statement, filed with the Commission on March 15,
         1994).

5        Opinion of Steven C. Root, Esq., with respect to the legality of
         securities being registered.

23(a)    Consent of KPMG Peat Marwick LLP.

23(b)    Consent of Steven C. Root, Esq. (included in Exhibit 5).

24       Powers of Attorney (included on the signature pages of Part II of the
         Registration Statement).