THIS FILING LISTS SECURITIES HOLDINGS REPORTED ON THE FORM 13F FILED ON FEBRUARY
14, 2007 PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT AND FOR WHICH
CONFIDENTIAL TREATMENT IS NO LONGER WARRANTED.

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              Washington D.C. 20549

                                    FORM 13F

                               FORM 13F COVER PAGE

Report for the Calendar Year or Quarter Ended: December 31, 2006

Check here if Amendment [X]: Amendment Number: 1

This Amendment (Check only one.):   [ ] is a restatement.
                                    [X] adds new holdings entries.

Institutional Investment Manager Filing this Report:

Name:      Chieftain Capital Management, Inc.
Address:   12 East 49th Street, New York, New York 10017

Form 13F File Number: 28-1658

The institutional investment manager filing this report and the person by whom
it is signed hereby represent that the person signing the report is authorized
to submit it, that all information contained herein is true, correct and
complete, and that it is understood that all required items, statements,
schedules, lists, and tables, are considered integral parts of this form.

Person Signing this Report on Behalf of Reporting Manager:

Name:    Thomas D. Stern
Title:   Managing Director
Phone:   (212) 421-9760

Signature, Place, and Date of Signing:


/s/ Thomas D. Stern                     New York, New York          May 15, 2007
- -------------------------------------   -------------------------   ------------

Report Type (Check only one.):

[X]  13F HOLDINGS REPORT. (Check here if all holdings of this reporting manager
     are reported in this report.)

[ ]  13F NOTICE. (Check here if no holdings reported are in this report, and all
     holdings are reported by other reporting manager(s).)

[ ]  13F COMBINATION REPORT. (Check here if a portion of the holdings for this
     reporting manager are reported in this report and a portion are reported by
     other reporting manager(s).)



                                    FORM 13F
                                  SUMMARY PAGE

Report Summary:

Number of Other Included Managers:                 0

Form 13F Information Table Entry Total:            1

Form 13F Information Table Value Total:     $177,002
                                          (thousands)

List of Other Included Managers:

Provide a numbered list of the name(s) and Form 13F file number(s) of all
institutional investment managers with respect to which this report is filed,
other than the manager filing this report.

NONE



                           FORM 13F INFORMATION TABLE



COLUMN 1                         COLUMN 2     COLUMN 3   COLUMN 4       COLUMN 5       COLUMN 6  COLUMN 7        COLUMN 8
- --------------------------------------------------------------------------------------------------------------------------------
                                 TITLE OF                 VALUE     SHRS OR  SH/ PUT/ INVESTMENT   OTHER     VOTING AUTHORITY
NAME OF ISSUER                    CLASS         CUSIP    [x$1000]   PRN AMT  PRN CALL DISCRETION MANAGERS    SOLE    SHARED NONE
- --------------------------------------------------------------------------------------------------------------------------------
                                                                                           
RYANAIR HOLDINGS PLC          SPONSORED ADR 783513 10 4 177,002   2,171,800  SH       SOLE                2,171,800