NYSE Arca, previously known as ArcaEx, an abbreviation of Archipelago Exchange, is a securities exchange on which both stocks and options are traded. It is owned by NYSE Euronext, which merged (as NYSE Group) with Archipelago Holdings in a reverse merger on 2006-02-27.

Early reports indicate that NYSE Arca may have played an early role in the 2010 Flash Crash

The NYSE Arca exchange is headquartered in Chicago, Illinois.

As of 1 March 2007, NYSE Arca is the second largest electronic communication network in terms of shares traded. Approximately one out of every six shares traded on the American financial markets is traded on the system. For New York Stock Exchange-listed securities or Tape A, it accounts for just over 10% of the shares traded. For NASDAQ-listed securities, NYSE Arca accounts for approximately 20% of the trading volume. For exchange-traded funds, NYSE Arca accounts for 30-40% of the traded volume.

NYSE Arca's liquidity fee/rebate structure resembles that of other electronic communication networks. In late 2006, it was the first one to offer NASDAQ-style fees on New York Stock Exchange-listed securities, a move that was soon copied by NASDAQ and other electronic communication networks. NYSE Arca charges traders that remove liquidity from the Arca-book $3.00 per 1,000 shares. Traders that add liquidity receive a $2.00 rebate per 1,000 shares. Traders that route orders out of the NYSE Arca system are charged $1.00 per 1,000 shares for Tape A securities and $4.00 per 1,000 shares for other securities.

The New York Stock Exchange, commonly referred to as NYSE is a stock exchange located at 11 Wall Street, Lower Manhattan, New York City, New York, United States. It is by far the world's largest stock exchange by market capitalization of its listed companies at US$14.242 trillion as of Dec 2011. Average daily trading value was approximately US$153 billion in 2008.

The NYSE is operated by NYSE Euronext (NYSE: NYX), which was formed by the NYSE's 2007 merger with the fully electronic stock exchange Euronext. The NYSE trading floor is located at 11 Wall Street and is composed of four rooms used for the facilitation of trading. A fifth trading room, located at 30 Broad Street, was closed in February 2007. The main building, located at 18 Broad Street, between the corners of Wall Street and Exchange Place, was designated a National Historic Landmark in 1978, as was the 11 Wall Street building.

The origin of the NYSE can be traced to May 17, 1792, when the Buttonwood Agreement was signed by 24 stockbrokers outside of 68 Wall Street in New York under a buttonwood tree on Wall Street. On March 8, 1817, the organization drafted a constitution and renamed itself the "New York Stock & Exchange Board." Anthony Stockholm was elected the Exchange's first president.

ARCA or Arca may refer to: