Reference is hereby made to (i) the Stockholders Agreement dated as of August 12, 1998 (the "Stockholders Agreement") by and among Global and the ---------------------- Stockholders, (ii) the Registration Rights Agreement dated as of August 12, 1998...
 
                                                                  EXHIBIT (c)(6)
                                                                  CONFORMED COPY
                                 AGREEMENT
          AGREEMENT (this "Agreement"), dated as of May 16, 1999, is entered
                           ---------                                        
into by Global Crossing Ltd. ("Global") and those other persons whose names
                               ------                                      
appear on the signature pages hereto (each, a "Stockholder" and collectively,
                                               -----------                   
the "Stockholders").
     ------------   
          Reference is hereby made to (i) the Stockholders Agreement dated as of
August 12, 1998 (the "Stockholders Agreement") by and among Global and the
                      ----------------------                              
Stockholders, (ii) the Registration Rights Agreement dated as of August 12, 1998
(the "Registration Rights Agreement") by and among Global and the Stockholders,
      -----------------------------                                            
(iii) the Agreement and Plan of Merger dated the date hereof (the "Merger
                                                                   ------
Agreement") between Global and U S West, Inc. ("USW") and (iv) the Tender Offer
---------                                                                      
and Purchase Agreement dated the date hereof (the "TOP Agreement") between
                                                   -------------          
Global and USW.
          In connection with the transactions pursuant to the Merger Agreement
and the TOP Agreement, the undersigned hereby agree as follows:
          1.  Clause (d) of Section 1 of the Stockholders Agreement shall be
     amended to read in its entirety as follows:  "(d) in a public offering
     pursuant to a registration statement under the Securities Act or a Transfer
     pursuant to Rule 144 under the Securities Act or pursuant to the tender
     offer under the Tender Offer and Purchase Agreement dated May 16, 1999
     between the Company and U S West, Inc."
          2.  Each Stockholder and Global agrees that USW shall have the right,
     in connection with any CoC Tag-Along Sale (as defined in the Stockholders
     Agreement) to participate in such sale on the same basis as any CoC Other
     Holder (as defined in the Stockholders Agreement) pursuant to Section 4(b)
     of the Stockholders Agreement.
          3.  Each Stockholder and Global agrees that, to give effect to the
     registration rights granted to USW by Global pursuant to Section 4.1 of the
     TOP Agreement, USW shall be treated as a Holder (as defined in the
     Registration Rights Agreement) for purposes of Sections 2(e) and 3(b) of
     the Registration Rights Agreement.
          4.  Global hereby agrees that it shall not unreasonably withhold its
      consent referenced in Section 2 of the Tender and Voting Agreement between
      USW and the Stockholders dated the date hereof.
          5.  This Agreement may be executed in counterparts, each of which when
       so executed shall be deemed to be an original, and such counterparts
       shall together constitute one and the same instrument. This Agreement
       shall be governed by and construed in accordance with the internal laws
       of the State of New York.
 
          IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the day and year first written above.
                              GLOBAL CROSSING LTD.
                              By:    /s/   ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇▇
                                 -----------------------------------------
                                  Title:  Chief Executive Officer         
                                                                          
                                                                          
                              CIBC WOOD GUNDY CAPITAL (SFC) INC.          
                                                                          
                                                                          
                              By:    /s/  ▇▇▇ ▇. ▇▇▇▇▇▇                   
                                 -----------------------------------------
                                  Title:  Agent                           
                                                                          
                                                                          
                              CIBC WG ARGOSY MERCHANT FUND 3, L.P.        
                                                                          
                                                                          
                              By:     /s/  ▇▇▇ ▇. ▇▇▇▇▇▇                  
                                 -----------------------------------------
                                  Title:  Managing Director
 
                                 CO-INVESTMENT MERCHANT FUND, LLC
                                 By:   /s/  ▇▇▇ ▇. ▇▇▇▇▇▇
                                    ------------------------------------------
                                    Title:  Agent                             
                                                                              
                                                                              
                                 CONTINENTAL CASUALTY CORPORATION             
                                 CONTINENTAL CASUALTY CORP.                   
                                 DESIGNATED HIGH YIELD FUND                   
                                                                              
                                                                              
                                 By:   /s/  ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇▇                 
                                    ------------------------------------------
                                    Title:  Authorized Signatory              
                                                                              
                                 MRCO, INC.                                   
                                                                              
                                                                              
                                 By:   /s/   ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇               
                                    ------------------------------------------
                                    Title:  President                         
                                                                              
                                                                              
                                       /s/  ▇▇▇▇ ▇▇▇▇▇▇▇                      
                                   -------------------------------------------
                                   ▇▇▇▇ ▇▇▇▇▇▇▇                                 
                                                                              
                                                                              
                                 PACIFIC CAPITAL GROUP, INC.                  
                                                                              
                                                                              
                                                                              
                                 By:   /s/  ▇▇▇▇ ▇▇▇▇▇▇▇                    
                                    ------------------------------------------
                                    Title: Chairman and Chief Executive Officer
                                                                              
                                                                              
                                 GKW UNIFIED HOLDINGS, LLC                    
                                                                              
                                                                              
                                 By:   /s/  ▇▇▇▇ ▇▇▇▇▇▇▇                    
                                    ------------------------------------------
                                    Title: Authorized Signatory               
                                                                              
 
                                       /s/   ▇▇▇▇▇▇ ▇. ▇▇▇▇▇                 
                                   -------------------------------------------
                                   ▇▇▇▇▇▇ ▇. ▇▇▇▇▇                              
                                                                              
                                                                              
                                 ▇▇▇▇▇ LIVING TRUST                           
                                 RIDGESTONE CORP.                             
                                                                              
                                                                              
                                 By:   /s/   ▇▇▇▇▇▇ ▇. ▇▇▇▇▇                
                                    ------------------------------------------
                                    Title:  President                         
                                                                              
                                                                              
                                       /s/  ▇▇▇▇▇ ▇▇▇▇▇▇                   
                                    ------------------------------------------
                                    ▇▇▇▇▇ ▇▇▇▇▇▇                   
                                                                              
                                                                              
                                 GALENIGHT CORP.                              
                                                                              
                                                                              
                                 By:   /s/  ▇▇▇▇▇ ▇▇▇▇▇▇                   
                                    ------------------------------------------
                                    Title:  President                         
                                                                              
                                                                              
                                                                              
                                       /s/  ▇▇▇▇▇ ▇▇▇                        
                                   -------------------------------------------
                                   ▇▇▇▇▇ ▇▇▇                                    
                                                                              
                                                                              
                                 SAN ▇▇▇▇▇▇▇ CORP.                            
                                                                              
                                                                              
                                 By:   /s/  ▇▇▇▇▇ ▇▇▇                       
                                    ------------------------------------------
                                    Title:  President                         
                                                                              
                                                                              
                                 ▇▇▇▇▇ AND ▇▇▇▇▇ ▇▇▇ FAMILY TRUST             
                                                                              
                                                                              
                                 By:   /s/  ▇▇▇▇▇ ▇▇▇                       
                                    ------------------------------------------
                                    Title:  Trustee                           
 
                                       /s/  ▇▇▇▇▇▇▇▇ ▇▇▇▇                    
                                   -------------------------------------------
                                   ▇▇▇▇▇▇▇▇ ▇▇▇▇                                
                                                                              
                                                                              
                                 GLOBAL CROSSING LTD., LDC                    
                                                                              
                                                                              
                                 By:   /s/  ▇▇▇ ▇. ▇▇▇▇▇▇                    
                                    ------------------------------------------
                                    Title:  Agent                             
                                                                              
                                                                              
                                 GLOBAL CROSSING TRUST 1998                   
                                                                              
                                                                              
                                 By:   /s/  ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇▇                 
                                    ------------------------------------------
                                    Title: Settlor                            
                                                                              
                                                                              
                                 GLOBAL CROSSING PARTNERS                     
                                                                              
                                                                              
                                 By:   /s/  ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇▇                 
                                    ------------------------------------------
                                    Title: General Partner                    
                                                                              
                                                                              
                                                                              
                                 CANADIAN IMPERIAL BANK OF COMMERCE           
                                                                              
                                                                              
                                 By:   /s/  ▇▇▇ ▇. ▇▇▇▇▇▇                    
                                    -------------------------------------------
                                    Title:  Agent
 
                                                            EXHIBIT A
 
▇▇▇▇▇ Living Trust                                          3,435,922
Ridgestone Corp.                                            7,765,418
                                                           ----------
Total ▇▇▇▇▇▇ ▇. ▇▇▇▇▇                                      11,201,340
                                                           
                                                           
▇▇▇▇▇ ▇▇▇▇▇▇                                                6,335,780
Galenight Corp.                                            11,883,968
                                                           ----------
Total ▇▇▇▇▇ ▇▇▇▇▇▇                                         18,219,748
                                                           
                                                           
Continental Casualty Corp.                                 16,795,500
Continental Casualty Corp. Designated High Yield           23,279,670
Global Crossing Partners (▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇▇)                  486,630
Global Crossing Trust 1998 (▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇▇)              2,100,000
                                                           ----------
Total Continental Casualty                                 42,661,800
                                                           
                                                           
CIBC WG Argosy Merchant Fund 3, LP                         17,223,628
CIBC Wood Gundy Capital (SFC) Inc.                          1,340,000
Co-Investment Merchant Fund, LLC                            9,568,684
Global Crossing Ltd., LDC                                  68,894,488
                                                           ----------
Total CIBC                                                 97,026,800
                                                           
                                                           
▇▇▇▇▇ and ▇▇▇▇▇ ▇▇▇ Family Trust                            5,233,234
▇▇▇▇▇ ▇. ▇▇▇                                                4,869,964
San ▇▇▇▇▇▇▇ Corp.                                           9,900,822
                                                           ----------
Total ▇▇▇▇▇ ▇▇▇                                            20,004,020
                                                           
                                                           
GKW Unified Holdings, LLC                                  77,195,744
Pacific Capital Group, Inc.                                15,993,406
                                                           ----------
Total ▇▇▇▇ ▇▇▇▇▇▇▇                                         93,189,150
                                                           
                                                           
▇▇▇▇▇▇▇▇ ▇▇▇▇                                               3,580,452
                                                           
                                                           
MRCo, Inc.                                                 33,180,260