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William P. O’Brien, SIOR

William P. O’Brien, SIORWilliam 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 21 years in the business. Average annual transaction values for Mr. O’Brien have been between $40,000,000 and $50,000,000. 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 Professional Standards Board, where he has undergone extensive training as an arbitrator and mediator. In addition, he has become 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.

Recently Mr. O’Brien was appointed chair of the Society of Industrial and Office Realtors (SIOR) Professional Standards Committee. In this position, Mr. O’Brien will oversee the committee’s management objectives and direct the activities of the committee to achieve implementation of these goals.

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 marketplace.


William P. O’Brien’s Listings

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William P. O’Brien’s Client List
  • Allstate Insurance
  • American Language Communication Centers
  • American Red Cross in Greater New York
  • Blockbuster Video
  • Brookdale Hospital Center
  • Brooklyn Bureau of Community Service
  • Brooklyn Chamber of Commerce
  • Brooklyn Hospital Center
  • Brooklyn Psychiatric Centers
  • Brooklyn Society for Prevention of Cruelty to Children
  • Burger King
  • Cadman Towers
  • Catholic Charities of Brooklyn & Queens, Inc.
  • Catholic Medical Center of Brooklyn & Queens, Inc.
  • Church Avenue Merchants Block Assn.
  • CVS Pharmacy Corp.
  • Dee & Dee Department Stores
  • Dunkin’ Donuts
  • Edward. D Jones
  • Eihab Human Services
  • Evelyn Douglin Center
  • Family Home Care of Brooklyn & Queens, Inc.
  • Genovese/Eckerd Drugs
  • Green Point Savings Bank
  • H&R Block
  • Hanson Place Dental Associates
  • Health Insurance Plan of NY, Inc.
  • HeartShare Inc.
  • Helen Keller Service for the Blind
  • Hollywood Video
  • Household Finance Corp.
  • Housing Works
  • Independence Community Bank
  • International Longshoremen’s Union
  • Jewish Board of Family & Children’s Services
  • JP Morgan Chase Manhattan Bank
  • King’s Kids
  • Long Island College Hospital
  • Maimonides Medical Center
  • McDonald’s
  • Metropolitan Life Insurance
  • Mount Sinai Medical Center
  • Nephrology Foundation of Brooklyn
  • New York Life
  • NY Methodist Hospital
  • NY ANA
  • NYC Citywide Administrative Services
  • NYC Health & Hospital’s Corp.
  • Partnership for the Homeless
  • Phillips Electronics North America
  • Polytechnic University
  • Rent-A-Center
  • RGIS Inventory Specialist
  • Ridgewood Saving Bank
  • Rite Aid Pharmacy Corp.
  • Seafarers International Union
  • St. Christopher DeOttilie
  • St. John’s School
  • St. Vincent’s Children’s Services
  • Sports and Fitness Centers, LLC
  • State Farm Insurance Co.
  • Sterling Dialysis Associates
  • Subway Sandwich
  • The Heights Casino
  • Touro College
  • Track Data Corp.
  • U.S. Navy
  • Walgreen’s Pharmacy
  • Washington Mutual Bank F.A.
  • Wyckoff Heights Hospital
  • Various Attorneys, Estates and Trusts