<PAGE>
 
                                  FORM 10-K/A
                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C.  20549

(X) ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d)
OF THE SECURITIES EXCHANGE ACT OF 1934 

For the fiscal year ended December 31, 1997

() TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
EXCHANGE ACT OF 1934 (NO FEE REQUIRED)

                          Commission File No. 0-22821
                             Cable Michigan, Inc.
            (Exact name of registrant as specified in its charter)
                  Pennsylvania                      23-2566891
           (State or other  jurisdiction of        (I.R.S. Employer
          incorporation or organization)          Identification No.)
 
           105 Carnegie Center, Princeton, New Jersey    08540
         (Address of principal executive offices)      (Zip Code)
 
    Registrant's telephone number including area code:    609-734-3737
    Securities registered pursuant to Section 12(b) of the Act:   None
          Securities registered pursuant to Section 12(g) of the Act:

                    Common Stock, par value $1.00 per share

                               (Title of Class)

Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was
required to file such reports), and (2) has been subject to such filing
requirements for the past 90 days.

                                X    Yes    No
Indicate by check mark if disclosure of delinquent filers pursuant to Item 405
of Regulation S-K is not contained herein, and will not be contained, to the
best of registrant's knowledge, in definitive proxy or information statements
incorporated by reference in Part III of this Form 10-K or any amendment to this
Form 10-K. (X)

Number of shares of the Registrant's Stock ($1.00 par value) outstanding at
February 28, 1998
                            6,872,040  Common Stock

Aggregate market value of Registrant's voting stock held by non-affiliates at
February 28, 1998 computed by reference to closing price as reported by NASDAQ
for Common Stock ($24.50 per share), is as follows:

                           $86,777,065  Common Stock

                      Documents Incorporated by Reference


                                     NONE
<PAGE>
 
Item 12.  Security ownership of certain beneficial owners and management.

The Company

The following table sets forth the beneficial ownership of Common Stock, as of
April 1, 1998, by each director, the named executive officers and by all
persons, as a group, who are currently directors and executive officers of the
Company.  Each director or executive officer has sole investment and voting
power over the shares listed opposite his name except as set forth in the
footnotes hereto:

<TABLE> 
<CAPTION> 
                                   NUMBER OF SHARES            PERCENT OF       
NAME OF BENEFICIAL OWNER         BENEFICIALLY OWNED (1)    OUTSTANDING SHARES
------------------------         ----------------------    ------------------
<S>                               <C>                       <C> 
R. Douglas Bradbury                      --                    --    
John J. Gdovin (2)                    1,743                      *
Bruce C. Godfrey (2)                  4,741                      *        
Mark Haverkate (2)                    4,596                      *        
Frank M. Henry                       16,140                      *        
David E. Knowles                        234                      *        
David C. McCourt (2)(3)              12,382                      *        
David C. Mitchell                       681                      *        
Raymond B. Ostroski                  18,419                      *        
Timothy J. Stoklosa                   1,014                      *        
All Directors and Executive          59,950                      *        
Officers as a Group (15 Persons)                                         
                                                                          
</TABLE>                                                                

(1)  Includes forfeitable Matching Shares (as defined below), and Share Units
     (as defined below).

(2)  Under the Cable Michigan Executive Stock Purchase Plan ("ESPP"),
     participating executive officers who forgo current compensation are
     credited with Cable Michigan "Share Units", the value of which is based on
     the value of a share of Cable Michigan Common Stock. ESPP participants who
     elect to receive Share Units in lieu of current compensation are also
     credited with restricted "Matching Shares," which vest over a period of 3
     years from the grant date, subject to continued employment. Matching
     Shares, unless forfeited, have voting and dividend rights. The holdings
     indicated include Share Units and Matching Shares. The table below shows,
     in respect of each Named Executive Officer, the number of shares of Cable
     Michigan Common Stock purchased outright, Share Units relating to Cable
     Michigan Common Stock acquired by each named executive officer in lieu of
     current compensation, and the forfeitable Matching Shares of Cable Michigan
     Common Stock held by each named executive officer:

<TABLE>
<CAPTION>
 
                                             SHARE UNITS                                TOTAL SHARES                         
                                           ACQUIRED UNDER                              PURCHASED AND                                
                                  SHARES     THE ESPP IN    TOTAL SHARES   RESTRICTED   ACQUIRED AND             
                               PURCHASED   LIEU OF CURRENT  PURCHASED AND   MATCHING    RESTRICTED                            
                                OUTRIGHT    COMPENSATION       ACQUIRED      SHARES    MATCHING SHARES                        
                               ---------   ---------------  -------------  ----------  ---------------
<S>                            <C>         <C>              <C>            <C>         <C>   
John J. Gdovin...............      677            533          1,210            533         1,743             
Bruce C. Godfrey.............    1,251          1,745          2,996          1,745         4,741             
Mark Haverkate...............    2,392          1,102          3,494          1,102         4,596             
David C. McCourt.............    2,894          4,744          7,638          4,744        12,382             
</TABLE>

<PAGE>
 

(3)  Includes 56 shares of Cable Michigan Common Stock which are owned by 
     Mr. McCourt's wife. Mr. McCourt disclaims beneficial ownership of such 
     shares. Does not include 3,330,121 shares of Cable Michigan common stock 
     held by LTH.

(4)  As a result of PKS separating its construction and mining management
     business ("Construction Group") from its other businesses on March 31, 1998
     (the "Split-Off"), PKS no longer owns an interest in the Construction
     Group. In conjunction with the Split-Off, PKS changed its name to "Level 3
     Communications, Inc." and the new PKS, the company formed in the Split-Off
     to hold the Construction Group's business, changed its name to "Peter
     Kiewit Sons', Inc. " Level 3 holds 90% of the common stock of LTH and all
     of the preferred stock of LTH. David C. McCourt owns the remaining 10% of
     the common stock of LTH. Level 3 has recently been merged into PKS and PKS
     has changed its name to Level 3 Communications, Inc. The address for each
     of Level 3 and LTH is 1000 Kiewit Plaza, Omaha, Nebraska 68131.

  The information set forth above and in "Director Information" does not give
effect to the ownership of Company securities by LTH.  Certain executive
officers or directors of the Company are directly or indirectly affiliated with
LTH.  For information with respect to the beneficial ownership of securities by
LTH, see "Security of Ownership Certain Beneficial Owners."

Mercom, Inc.

Set forth below is certain information regarding the beneficial ownership of the
Common Stock of Mercom, a 61.92% owned subsidiary of the Company, as of April 1,
1998, by each director, the named executive officers and by all persons, as a
group, who are currently directors and executive officers of the Company. Each
director or executive officer has sole investment and voting power over the
shares listed opposite his name except as set forth in the footnotes hereto:

<TABLE>
<CAPTION>
                                NUMBER OF SHARES    PERCENT                  
NAME OF BENEFICIAL OWNER       BENEFICIALLY OWNED   OF CLASS                 
------------------------       ------------------   --------                 
<S>                            <C>                  <C> 
R. Douglas Bradbury                     --             --
John J. Gdovin                          --             --                    
Bruce C. Godfrey                        --             --                    
Mark Haverkate                          --             --
Frank M. Henry                          --             --
Daniel E. Knowles                       --             --
David C. McCourt                        --(1)          --                    
David C. Mitchell                       --             --
Raymond B. Ostroski                  4,000              *                    
Timothy J. Stoklosa                     --             --                    
All Directors and Executive                                          
Officers as a Group (15 persons)     4,000              *                    
</TABLE>

____________________________
*  Less than 1% of the outstanding shares.

/(1)/ Excludes 50,000 shares which are owned by Mr. McCourt's wife.  Mr. McCourt
disclaims beneficial ownership of such shares.
<PAGE>
 
                                   SIGNATURES
                                        
Pursuant  to the requirements of Section 13 or 15(d) of the Securities Exchange
Act of 1934, the Registrant has duly caused this report to be signed on its
behalf by the undersigned, thereunto duly authorized.

                 Cable Michigan, Inc.

Date:  May 6, 1998         By /s/ David C. McCourt
                             --------------------
                             David C. McCourt
                             Chairman and Chief Executive Officer

Pursuant to the requirements of the Securities Exchange Act of 1934, this report
has been signed below by the following persons on behalf of the Registrant and
in the capacities and on the dates indicated.


     Signature                   Title                   Date
     ---------                   -----                   ----

PRINCIPAL EXECUTIVE AND ACCOUNTING OFFICERS:
 
 
/s/ David C. McCourt             Chairman and Chief      May 6, 1998 
---------------------------      Executive Officer
David C. McCourt                 

 
 /s/ Mark Haverkate              President and Chief     May 6, 1998 
---------------------------      Operating Officer
   Mark Haverkate             

 
 /s/ Timothy J. Stoklosa         Executive Vice          May 6, 1998 
---------------------------      President and
   Timothy J. Stoklosa           Chief Financial
                                 Officer
 

 /s/ Ralph S. Hromisin           Vice President and      May 6, 1998 
---------------------------      Chief Accounting
   Ralph S. Hromisin             Officer