The city of Stamford, in Connecticut,  became the North American headquarters of UBS in 2002 and the Royal Bank of Scotland in 2006. Stamford has been nicknamed “Wall Street North” since at least 2009.
 
Connecticut’s Fourth District (including Stamford) has also been called “Wall Street on Long Island Sound.”
     
 
Wikipedia: Stamford, Connecticut
Stamford is a city in Fairfield County, Connecticut, United States. According to the 2010 census, the population of the city is 122,643, making it the fourth largest city in the state and the eighth largest city in New England. Stamford is in the Bridgeport-Stamford-Norwalk Metro area which is a part of the Greater New York metropolitan area.

Wall Street Journal
MAY 6, 2009
Trouble in ‘Wall Street North’ Spurs Search for New Identity
By KELLY EVANS
STAMFORD, Conn.—In 2002, UBS AG built North America’s biggest trading floor here. Not to be outdone, rival Royal Bank of Scotland broke ground across the street in 2006, planning its own lavish headquarters—and a trading floor nearly as large.
 
Then the turmoil on Wall Street began, shaking and shrinking these giants of the financial-services industry.

So what is next for the city that has garnered the reputation, at least locally, as “Wall Street North?”
   
Streets of Stamford
Saturday, May 9, 2009
WSJ on the CTW, UBS, RBS, $$$
The Wall Street Journal noticed us! There’s an article on WSJ.com about how the financial crisis has impacted Stamford and what the city is doing about it. It’s pretty interesting, although I’ve never heard the phrase “Wall Street North.” I usually call Stamford “Bridgeport South.” I kid, I kid.
 
Wall Street Journal
AUGUST 10, 2010
Incomes Fall in Most Metro Areas
By CONOR DOUGHERTY
(...)
Bridgeport-Stamford, a hedge fund hub known locally “Wall Street North,” remained the country’s richest metropolitan area—with per capita income of $73,720 despite a 6.8% decline from a year ago.
 
Wall Street Journal—Speakeasy
October 17, 2011, 10:00 AM ET
Occupying Cleveland and Rome, but Not ‘Wall Street North’
By WSJ Staff
The North American headquarters of two of the world’s biggest banks are on proud display here. So why isn’t anyone occupying Stamford?
 
This Connecticut city, a quick, 50-minute train ride from midtown Manhattan, was once replete with the sprawling, manicured campuses of corporate America. Today, in a transformation echoing that of the country’s at large, it has earned the nickname “Wall Street North.” The hulking, opposing homes of Swiss bank UBS and Britain’s RBS Group now stand like the Pillars of Hercules as both a gateway to the city and a symbol of it.