SIXTH AMENDMENT TO LEASE

Exhibit 10.1

Certain portions hereof denoted with “[***]” have been omitted pursuant to a Request for

Confidential Treatment and have been filed separately with the Commission

SIXTH AMENDMENT TO LEASE

THIS SIXTH AMENDMENT TO LEASE (this “ Amendment ”) is made as of this 1st day of May, 2007, by and between HULL POINT LLC, a Maryland limited liability company (“ Landlord ”) and UNDER ARMOUR, INC., a Maryland corporation (“ Tenant ”), formerly known as KP Sports, Inc.

R.1. By that Office Lease dated March 29, 2002 by and between Landlord and Tenant, as amended by: (a) that First Amendment to Lease dated September 10, 2002, (b) that Second Amendment to Lease dated March 6, 2003, (c) that Third Amendment to Lease dated June 23, 2004, (d) that Fourth Amendment to Lease dated October 12, 2006, and (e) that Fifth Amendment to Lease dated December 1, 2006 (collectively, the “ Existing Lease ”), Landlord leased to Tenant those certain premises consisting of: (i) 31,880 rentable square feet of space on the third floor, (ii) 4,661 rentable square feet of space on the fourth floor, (iii) 463 rentable square feet on the bridge of the Ivory Building, (iv) 8,581 rentable square feet of space on the second floor of the Dawn Building, and (v) 4,400 rentable square feet of space on the second floor bridge between the Tide and Ivory Buildings (the “ Existing Premises ”) located at Tide Point, 1020 Hull Street, Baltimore, Maryland 21230 (the Existing Lease together with this Amendment are referred collectively as the “ Lease ”).

R.2. Landlord and Tenant desire to amend the terms and conditions of the Existing Lease to reflect: (a) an expansion of the Existing Premises by (i) 5,000 rentable square feet of space on the second floor of the Tide Building (“ Suite 200 ”), (ii) 12,594 rentable square feet of space on the third floor of the Tide Building (“ Suite 300 ”), and (iii) 1,673 rentable square feet of space on the second floor of the Tide Building (“ Suite 210 ”), all as more particularly depicted on Exhibit A (referred to as the “ Expansion Space ”); and (b) to modify and extend the Term of the Lease as described below.

R.3. Landlord and Tenant desire to amend the Lease upon the terms and conditions set forth below.

AGREEMENT

NOW, THEREFORE, for good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, Landlord and Tenant agree as follows:

1. Definitions . All capitalized terms not otherwise defined herein shall have the meanings ascribed to them in the Lease. May 1, 2007 will constitute the “ Effective Date .”

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2. Amendments to Lease . The Lease is hereby amended as follows:

2.1 Lease Term . The Existing Lease currently has several expiration dates, each tied to a portion of the Existing Premises. All such expiration dates are hereby superceded and the Term of the Lease shall, unless otherwise provided in this Amendment or in the Lease, be until April 30, 2012. For purposes of establishing the Base Rent, the period from May 1, 2007 until April 30, 2008 shall be Lease Year 1, and each subsequent twelve calendar month period shall be the next succeeding Lease Year.

2.2 Rent .

(a) Through April 30, 2007, Tenant shall be responsible for paying Base Rent in accordance with the Existing Lease. As of the Effective Date, Base Rent will be determined in accordance with the following provisions of this Amendment, notwithstanding the various rent schedules applicable beyond that date set forth in the Fourth and Fifth Amendments.

(b) Tenant shall pay Base Rent for the Existing Premises and the 5,000 rentable square feet of Suite 200 as follows:

(c) Tenant shall pay Base Rent for the 12,594 rentable square feet of Suite 300 as follows:

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(d) Tenant shall pay Base Rent for the 1,673 rentable square feet of Suite 210 as follows:

2.3 Delivery of Expansion Spaces . Landlord shall deliver the Expansion Space to the Tenant on May 1, 2007. As of the delivery date above, the definition of the term “Premises” shall include the Expansion Space, and the rentable square footage of the Premises shall be increased to 69,272. Tenant shall accept the