UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

o

Rule 13d-1(b)

o

Rule 13d-1(c)

x

Rule 13d-1(d)

CUSIP No. 465685 10 5

1.

Names of Reporting Persons. International Transmission Holdings Limited Partnership
I.R.S. Identification Nos. of above persons (entities only) 20-0151114

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
Michigan

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
11,390,054

6.

Shared Voting Power
0

7.

Sole Dispositive Power
11,390,054

8.

Shared Dispositive Power
0

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
11,390,054

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
26.9%**

12.

Type of Reporting Person (See Instructions)
PN

CUSIP No. 465685 10 5

1.

Names of Reporting Persons. Ironhill Transmission, LLC
I.R.S. Identification Nos. of above persons (entities only) 20-0152053

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
Michigan

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
11,390,054*

6.

Shared Voting Power
0

7.

Sole Dispositive Power
11,390,054*

8.

Shared Dispositive Power
0

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
11,390,054*

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
26.9%**

12.

Type of Reporting Person (See Instructions)
OO

CUSIP No. 465685 10 5

1.

Names of Reporting Persons. Lewis M. Eisenberg
I.R.S. Identification Nos. of above persons (entities only): N/A

2.

Check the Appropriate Box if a Member of a Group (See Instructions)

(a)

o

(b)

o

3.

SEC Use Only

4.

Citizenship or Place of Organization
United States

Number of
Shares
Beneficially
Owned by
Each
Reporting
Person With

5.

Sole Voting Power
11,392,505*

6.

Shared Voting Power
0

7.

Sole Dispositive Power
11,392,505*

8.

Shared Dispositive Power
0

9.

Aggregate Amount Beneficially Owned by Each Reporting Person
11,392,505*

10.

Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions)  o

11.

Percent of Class Represented by Amount in Row (9)
26.9%**

12.

Type of Reporting Person (See Instructions)
IN

This Amendment No. 1 supplements and amends Items 4 and 5 of the statements on Schedule 13G (the “Schedule 13G”) relating to the common stock, without par value (the “Common Stock”), of ITC Holdings Corp., a Michigan corporation (“ITC Holdings”), filed on February 14, 2006 by each of International Transmission Holdings Limited Partnership (“ITHLP”), Ironhill Transmission, LLC (“Ironhill”) and Lewis M. Eisenberg (“Eisenberg”).  Each Item below amends and supplements the information disclosed under the corresponding Item of the Schedule 13G.

Item 4.

Ownership

Item 4 of the Schedule 13G is hereby amended and supplemented by deleting it in its entirety and replacing it with the following:

Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.

(a)

Amount beneficially owned:   

See Item 9 of the cover pages of Amendment No. 1 to this Schedule 13G.

(b)

Percent of class:   

See Item 11 of the cover pages of Amendment No. 1 to this Schedule 13G.

(c)

Number of shares as to which the person has:

(i)

Sole power to vote or to direct the vote    

See Item 5 of the cover pages of Amendment No. 1 to this Schedule 13G.

(ii)

Shared power to vote or to direct the vote    

See Item 6 of the cover pages of Amendment No. 1 to this Schedule 13G.

(iii)

Sole power to dispose or to direct the disposition of   

See Item 7 of the cover pages of Amendment No. 1 to this Schedule 13G.

(iv)

Shared power to dispose or to direct the disposition of   

See Item 8 of the cover pages of Amendment No. 1 to this Schedule 13G.

Item 5.

Ownership of Five Percent or Less of a Class

Item 5 of the Schedule 13G is hereby amended and supplemented by deleting it in its entirety and replacing it with the following:

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following  x.

On February 6, 2007, ITHLP distributed an aggregate of 2,125,520 shares of Common Stock to its partners (the “Distribution”), including 9,573 shares of Common Stock to its general partner, Ironhill.  On February 12, 2007, pursuant to the Underwriting Agreement dated February 6, 2007 among ITC Holdings, ITHLP and Credit Suisse Securities (USA) LLC (the “Underwriter”), ITHLP sold 6,826,287 shares of Common Stock to the Underwriter in a registered public secondary offering (the “Public Offering”) pursuant to ITC Holdings’ registration statement on Form S-3 filed with the Securities and Exchange Commission on January 17, 2007 (File No. 333-140026).  On February 12, 2007, pursuant to the Purchase and Sale Agreement dated February 6, 2007 among ITHLP and Ecofin Water & Power Opportunities Plc., Ecofin Global Utilities Master Fund Limited and Ecofin Special Situations Utilities Master Fund Limited (collectively, the “Ecofin Funds”), acting through their manager, Ecofin Limited, ITHLP sold an aggregate of 1,323,247 shares of Common Stock to the Ecofin Funds (the “Ecofin Sale”).  As a result of the Distribution, the Public Offering and the Ecofin Sale, each of ITHLP, Ironhill and Eisenberg ceased to be the beneficial owner of more than 5% of the Common Stock on February 12, 2007.