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William P. O'Brien
SIOR

Office Specialist

M.C. O'Brien, Inc.

4718 Avenue N, Brooklyn, NY 11234

Market
New York
Specialty
Office Specialist
Member Since
1997
Chapter
SIOR New York City and Downstate Chapter
Areas of Practice
Tenant Representation, Landlord, Sale/Leasing, Investments, Consulting
Accreditations
SIOR
William P. O'Brien, SIOR, is a third generation member of M. C. O'Brien, Inc., which is currently the oldest commercial real estate firm operating in Brooklyn. Mr. O'Brien has been associated with the Brooklyn Board of Realtors since entering the real estate business in 1989 and has continued to refine his professional abilities through education, networking and his affiliation with a diverse group of commercial real estate organizations. Specifically, during his tenure at The Brooklyn Board of Realtors he became interested in the Professional Standards and Mediation component of the Realtor Designation and ultimately chaired the Professional Standards and Mediation Committee for a number of years.

Mr. O'Brien has been able to achieve considerable success in terms of retail and office leasing and sales in his 29 years in the business. Aggregate transaction volume is just shy of $2,000,000.000.00. Mr. O'Brien has represented numerous entities in regard to their real property needs in Brooklyn and Queens, including State Farm Insurance, JP Morgan Chase, Rite Aid Pharmacy, Walgreens Pharmacy, Allstate Insurance, the American Red Cross and a host of community-based organizations and entrepreneurs.

Mr. O'Brien earned the hard-to-attain designation of Specialist in Industrial and Office Real Estate (SIOR) in 1997. He was, at that time, one of the youngest people ever to achieve this goal in metro New York. He was President of the Downstate New York Chapter of SIOR in 2008 and 2009, and serves on the National SIOR Professional Standards Board, where he has undergone extensive training as an arbitrator and mediator. In addition, he was a Trustee of the SIOR Foundation, which promotes the commercial real estate industry through a host of educational programs and scholarships. SIOR is viewed by many as the consummate commercial real estate designation, with members required to show proficiency in their respective discipline in either office or industrial brokerage. Members have to demonstrate a minimum amount of aggregate transaction volume and adhere to strict educational requirements as well as professional standards.

The majority of Mr. O'Brien's work focuses on commercial leasing both for tenants and landlords but he is also an active sales broker having secured numerous all cash transactions for his clients with limited due diligence over the last few years. In addition to advising corporate clients, one of his significant niches is working with a wide variety of not-for-profit entities providing services to the diverse Brooklyn and Queens’s marketplace.

Mr. O'Brien became a Board Member of Brooklyn Community Services, formerly The Brooklyn Bureau of Community Service, the largest non-sectarian social service provider in Brooklyn. Recently his tenure was up but he continues to advise BCS in regard to their Real Estate needs.

Mr. O'Brien resides in Rockville Centre, NY with his wife of 27 years, Ann Marie, and their three children, Christopher, Evan and Lauren.
  • Multi Year Costar Power Broker Recipient
  • University of Vermont and Hofstra University
William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Office Lease
$723,412
5,730 Sq. Ft.
September 15, 2019 Brooklyn, NY

William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Office Lease
$4,066,200
8,800 Sq. Ft. / 10,000 Sq. Ft. Space
September 1, 2019 Brooklyn, NY

William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Office Lease
$68,000,000
50,765 Sq. Ft.
August 28, 2019 Elmhurst, NY

William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Office Sale
$11,300,000
32,000 Sq. Ft. / 100,000 Sq. Ft. Space
February 14, 2019 Brooklyn, NY

William represented Emblem Health

William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Other Lease
$3,000,000
4,200 Sq. Ft. / 4,200 Sq. Ft. Space
February 12, 2019 Brooklyn, NY

William represented Diana Realty

William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Office Lease
$2,865,000
9,000 Sq. Ft.
September 15, 2018 Brooklyn, NY

William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Office Lease
$2,600,000
9,100 Sq. Ft.
August 1, 2018 Brooklyn, NY

William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Office Sale
$12,500,000
48,000 Sq. Ft. / 30,000 Sq. Ft. Space
July 27, 2018 Brooklyn, NY

William represented The Arker Companies

William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Office Lease
$3,812,000
11,250 Sq. Ft.
July 23, 2018 Brooklyn, NY

William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Other Sale
$7,700,000
40,000 Sq. Ft. / 30,000 Sq. Ft. Space
July 20, 2018 Brooklyn, NY

William represented Rentar Development

William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Office Lease
$2,685,000
7,200 Sq. Ft.
July 15, 2018 Brooklyn, NY

William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Jack Britvan, SIOR
Commercial Realty Services of Long Island
Jericho, NY
Office Lease
$20,000,000
42,000 Sq. Ft.
May 15, 2016 Brooklyn, NY

William represented Dime Savings Bank of Williamsburg

Jack represented Dime Savings Bank of Williamsburg

Robert Hebron, SIOR
Ingram & Hebron Realty
Brooklyn, NY
William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Office Lease
$1,350,000
2,500 Sq. Ft.
March 2, 2015 Brooklyn, NY

William represented Sylvan Learning

William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Robert Hebron, SIOR
Ingram & Hebron Realty
Brooklyn, NY
Office Lease
$539,097
4,000 Sq. Ft.
February 1, 2015 Brooklyn, NY

William represented Paul J. Cooper Center for Human Sevices., Inc.

Robert represented Paul J. Cooper Center for Human Sevices., Inc.

Lloyd Cooper, SIOR, BCL, LLB, MBA, MCR
Cushman & Wakefield
Montreal, QC
William O'Brien, SIOR
M.C. O'Brien, Inc.
Brooklyn, NY
Office Sale
$966,000
February 1, 2011 Queens, NY

Professional Standards
  • Role : Member
  • Begin Date : 10/1/2019
  • End Date : 9/30/2020
SPB - Tenant Representation
  • Role :
  • Begin Date : 1/1/2006
  • End Date : 1/1/2020
Professional Standards
  • Role : Chair
  • Begin Date : 10/1/2016
  • End Date : 9/30/2018
SIOR Foundation Board of Trustees
  • Role : Member
  • Begin Date : 10/24/2013
  • End Date : 10/20/2016
SIOR Foundation Grants & Scholarship
  • Role : Member
  • Begin Date : 10/8/2015
  • End Date : 10/20/2016
Professional Standards
  • Role : Vice Chair
  • Begin Date : 10/1/2014
  • End Date : 9/30/2016
GSA Reporter
  • Role :
  • Begin Date : 1/1/2006
  • End Date : 12/31/2015
SIOR Foundation Grants & Scholarship
  • Role : Member
  • Begin Date : 10/23/2014
  • End Date : 10/8/2015
Committee Council Leadership
  • Role : Vice Chair
  • Begin Date : 10/1/2014
  • End Date : 9/30/2015
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