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                                                                      EXHIBIT 4
 
                                  FRONT SIDE
 
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                                    MapInfo
                       THE INFORMATION DISCOVERY COMPANY
 
MI
 
             INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE
 
       THIS CERTIFICATE IS TRANSFERABLE IN BOSTON, MA. OR NEW YORK, N.Y.
 
COMMON STOCK                                                  CUSIP 565105 10 3
                                            SEE REVERSE FOR CERTAIN DEFINITIONS
 
This CERTIFIES that
 
is the owner of
 
          FULLY PAID AND NON-ASSESSABLE SHARES OF THE COMMON STOCK OF
 
MAPINFO CORPORATION, transferable on the books of the Corporation by said
owner in person, or by duly authorized attorney, upon surrender of this
certificate properly endorsed. This certificate and the shares represented
hereby are subject to all the terms, conditions and limitations of the
Certificate of Incorporation and all amendments thereto and supplements
thereof.
 
  This certificate is not valid until countersigned and registered by the
Transfer Agent and Registrar.
 
  WITNESS the facsimile seal of the Corporation and the facsimile signatures
of the Corporation's duly authorized officers.
 
Dated:
 
Countersigned and Registered:
BankBoston, N.A.
Transfer Agent
and Registrar,
By
 
Authorized Signature
 
/s/ John F. Haller                          /s/ John C. Cavalier
Secretary                SEAL               President and Chief Executive
                                            Officer
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                                   BACK SIDE
 
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                                    MapInfo
                       THE INFORMATION DISCOVERY COMPANY
 
  THE CORPORATION WILL FURNISH WITHOUT CHARGE TO EACH STOCKHOLDER WHO SO
REQUESTS, A FULL STATEMENT OF THE DESIGNATIONS, RELATIVE RIGHTS, PREFERENCES
AND LIMITATIONS OF EACH CLASS OF STOCK OR SERIES THEREOF AUTHORIZED TO BE
ISSUED AND THE AUTHORITY OF THE BOARD OF DIRECTORS OF THE CORPORATION TO
DESIGNATE AND FIX THE RELATIVE RIGHTS, PREFERENCES AND LIMITATIONS OF CLASSES
OF PREFERRED STOCK IN SERIES.
 
  The following abbreviations, when used in the inscription on the face of
this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:
 
TEN COM--as tenants in common     UNIF GIFT MIN ACT--      Custodian       ,
TEN ENT--as tenants by the                             (Cust)           (Minor)
entireties
 
JT WROS--as joint tenants with     Under Uniform Gifts to Minors Act __________
         right of survivorship                                      (State)
         and not as tenants in
         common
 
    Additional abbreviations may also be used though not in the above list.
 
For value received,                hereby sell, assign and transfer unto
 
PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE
 
(Please print or typewrite name and address including postal zip code of
assignee)
 
Shares
 
of the Common Stock represented by the within Certificate, and do hereby
irrevocably constitute and appoint
 
Attorney
 
to transfer the said Shares on the books of the within-named Corporation with
full power of substitution in the premises.
 
Dated:
 
NOTICE: The signature to this assignment must correspond with the name as
written upon the face of the certificate in every particular, without
alteration or enlargement, or any change whatever.
 
SIGNATURE(S) GUARANTEED:
 
THE SIGNATURE(S) SHOULD BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION
(BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH
MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM), PURSUANT TO
S.E.C. RULE 17Ad-15.