Sitt was born in 1964 near Coney Island, Brooklyn to a Syrian Jewish family. He began working at a young age in flea market booths at the Aqueduct and Roosevelt racetrack parking lots in the New York City area. At age 11, Sitt became interested in real estate when his only choice was to go to Manhattan to buy an Atari computer because he couldn't get one in Brooklyn. This eventually led Sitt to study business at New York University's Stern School of Business, and in 1986 he founded Thor Equities before graduating.
Sitt picked the name Thor for the company because he was an avid Thor comic book fan and thought it would fit his "concept of being the protector of the cities." His first investment was a property sold at tax auction on East Tremont Avenue in the Bronx, a chronically underserved retail area, where he built a one-story retail structure with money from "family, friends, roommates, parents of roommates." He proceeded to secure national retailers Rite Aid Pharmacy, Payless Shoes, and Rainbow Shops. In 1989, partnering with Joseph Chehabar of the family that owned Rainbow Shops, he purchased for $30 million the 161-store Children’s Place retail chain and the 41-store Accessory Place retail chain from the Campeau Corporation. As part of the transaction, they then sold Accessory Place to Tribeca Corporation.
From Sitt’s early realization of the retail gap that left broad swathes of inner city consumers largely underserved by major retailers, in 1991 he founded Ashley Stewart (a name inspired by Laura Ashley and Martha Stewart), which sold modern and fashionable plus-size clothing to urban women. Each Ashley Stewart store hired from within the community, and the company was recognized by President Clinton for its large contribution to the nation’s innovative Welfare to Work program. After acquiring 98 stores for $61.25 million in 1998 from the bankrupt Petrie Retail Inc. (founded by Milton Petrie), Ashley Stewart grew to over 380 stores in more than 100 cities, which prompted many national retailers to follow suit and helped change the urban retail landscape. As part of the transaction with Petrie Retail, Sitt acquired Marianne Stores, a retail outlet specializing in clothing for Latina women. As business boomed, Sitt sold his interest in 2000 to concentrate on urban real estate through his company Thor Equities.
In 2004, Sitt was profiled by Crains in its annual "40 Under 40" article, which reported that he had a 6 million square-foot portfolio worth nearly $750 million. In 2010, he started a brokerage business called Thor High Street (Thor Retail Advisors) that focuses on retail leasing.
Today, Thor Equities is a global leader in real estate development, leasing and management of commercial, residential, retail, hotel and mixed-use assets, with headquarters in New York City, London and Mexico City. The company owns property in the United States, Canada, Europe, Russia, India and Latin America, with portfolio transactions and a development pipeline in excess of $10 billion and totaling more than 20 million square feet.
Joseph Sitt is the chairman and founder of the not-for-profit Global Gateway Alliance (GGA), which was created in 2012 to address the infrastructure challenges that New York metropolitan area airports face. Sitt made an initial $1 million donation to start the group, which seeks to make New York’s airports among the best in the world. On July 27, 2015, Vice President Joseph Biden and Gov. Andrew Cuomo announced plans to modernize JFK and LaGuardia airports, which included many of the features Sitt and GGA long called for, including new terminals, greater passenger amenities, and increased transportation access. Accordingly, GGA Chairman Joseph Sitt stated this was "an important step in bringing New York’s airports into the 21st century, and a win for the more than 117 million annual passengers that use our airports and for a regional economy that relies on the airports for more than $50 billion in activity."
Joseph Sitt is an active board member of the Bedford Stuyvesant Restoration Corporation, one of the most respected community development organizations in the United States. He was instrumental in helping restore Restoration Plaza, the neighborhood’s Town Square and the BSRC’s main asset, and bringing to the area more retail options including its first family sit-down restaurant and supermarket. In 2007, Harvard professor Michael Porter and the Initiative for a Competitive Inner City (ICIC) honored him for his commitment to fostering healthy competitive business conditions and new opportunities in inner city neighborhoods.
Sitt is a managing director of Venetian Heritage, a not-for-profit organization that works to restore the Jewish museum and ancient synagogues of the Ghetto of Venice.
Sitt is also a frequent speaker and lecturer at various universities including Columbia University, New York University, Baruch, and Notre Dame. He serves on the board of the Real Estate Roundtable in Washington D.C., the Department of Real Estate at Baruch College, and is a member of the Partnership for New York City.
Sitt has served on the boards of the Downtown Brooklyn Council economic development advocacy group, REBNY’s Board of Governors, and as co-chairman of the Brooklyn Fulton Street Business Improvement District.
He has spent much of his career in youth development and education, serving on the Boards of Brooklyn’s TAB High School and Flatbush High School, leading a teen program and acting as an ongoing mentor and guidance counselor to Brooklyn youth.
Mr. Sitt was awarded the 2014 Ernst and Young Entrepreneur of the Year Award, and has been named by New York Observer in its annual list as one of the Most Powerful People in New York Real Estate.