Brokers Offering Portfolio Margin

Ever since the approval of Portfolio Margin in 2007, brokers began offering portfolio margin accounts to their clients. Surprisingly, many of the largest online discount brokers have yet to add Portfolio Margin capabilities. Below is a list of brokers offering Portfolio margin accounts. 
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*This list was last updated on May 13, 2012
Interactive Brokers - YES
IB was one of the first brokers to offer Portfolio Margin. Their extremely low commission rates, low margin borrowing rates, and sophisticated TraderWorkstation platform make IB one of the best brokers out there for advanced traders.
E*TRADE - YES
This former titan of online trading was late to the game and only began offering portfolio margin in Sept, 2011. 
TD Ameritrade/Think or Swim - YES
TD Ameritrade offers portfolio margin through their Think or Swim subsidiary (acquired by TD in 2009). That said, apparently there have been some problematic issues regarding the integration of the ThinkorSwim system. Also, apparently they set their minimum net asset value requirement is $125,000 for Portfolio Margin accounts (compare to 100k for most other brokers).
Charles Schwab/Options Xpress - YES
options Xpress (acquired by Charles Schwab in 2011) focuses on options and futures trading and offers portfolio margin.  
Optionshouse - YES
Optionshouse offers Portfolio Margin, albeit it is unclear if this is only for their institutional clients or if they offer it to retail investors.
Lightspeed Trading - YES
Lightspeed Trading offers Portfolio Margin.
Newedge  - YES
The former Fermat USA, Newedge was one of the first broker to offer Portfolio Margin.
Victor Securities - YES
Victor Securities offers Portfolio Margin.
TradeMonster  - YES
TradeMonster began offering Portfolio Margin in April, 2012. 
TradeStation - NO
TradeStation does not offer Portfolio Margin.
Scottrade - NO
Scottrade does not offer Portfolio Margin. 
Fidelity - NO
Fidelity does not offer Portfolio Margin.
TradeKing - NO
TradeKing does not offer Portfolio Margin. In 2011 TradeKing stated that it changed clearing firms and is now exploring the idea of offering Portfolio Margin. You can find some basic information in their website's FAQs. Unfortunately, it appears that no major progress has been made. 
FIRSTRADE - NO
FIRSTRADE does not offer Portfolio Margin.
Merrill Edge - NO
Merrill Edge does not offer Portfolio Margin.
Zecco - NO
Zecco does not offer Portfolio Margin.
Just2Trade - NO
Just2Trade does not offer Portfolio Margin.
Choice Trade - NO
Choice Trade does not offer Portfolio Margin.
SogoTrade - NO
SogoTrade does not offer Portfolio Margin.
MB Trading - NO
MB Trading does not offer Portfolio Margin.
In order to offer Portfolio Margin Accounts a broker must meet the stringent compliance and risk requirements of their Designated Examining Authority (the NYSE for most brokers). 
*Any errors in this list can be reported by contacting the site admin.