Question: What stock exchange lists a competitor of Ladbrokes?

Context paragraphs:
San Francisco Stock and Bond Exchange: The San Francisco Stock and Bond Exchange was a regional stock exchange based in San Francisco, California, United States.  Founded in 1882, in 1928 the exchange purchased and began using the name San Francisco Stock Exchange, while the old San Francisco Stock Exchange was renamed the San Francisco Mining Exchange.  The San Francisco Curb Exchange was absorbed by the San Francisco Stock Exchange in 1938.  In 1956 the San Francisco Stock Exchange merged with the Los Angeles Oil Exchange to create the Pacific Coast Stock Exchange.

Karachi Stock Exchange: The Karachi Stock Exchange Limited (KSE), was a stock exchange located at the Stock Exchange Building (SEB) on Stock Exchange Road, in the heart of Karachi's Business District, I. I. Chundrigar Road, Karachi, Sindh Province of Pakistan.  It is now incorporated in the Pakistan Stock Exchange along with the other two bourses of Pakistan, the Lahore Stock Exchange and the Islamabad Stock Exchange It is Pakistan's largest and one of the oldest stock exchange in South Asia by market capitalization, with many Pakistani consortium as well as overseas enterprises listings.

Nigerian Stock Exchange: The Nigerian Stock Exchange (NSE) was established in 1960 as the Lagos Stock Exchange.  In 1977, its name was changed from the Lagos Stock Exchange to the Nigerian Stock Exchange.  As at March 7, 2017, it has 176 listed companies with a total market capitalization of about N8.5 trillion.  All listings are included in the Nigerian Stock Exchange All Shares index.  In terms of market capitalization, the Nigerian Stock Exchange is the third largest stock exchange in Africa.

Betting shop: In the United Kingdom, a betting shop is a shop away from a racecourse ("off-course") where one can legally place bets in person with a licensed bookmaker such as William Hill, Ladbrokes, or John mulhollands.

Nasdaq, Inc.: Nasdaq, Inc. is an American multinational financial services corporation that owns and operates (and is listed on) the NASDAQ (formerly National Association of Securities Dealers Automated Quotations) stock market and eight European stock exchanges, namely Armenian Stock Exchange, Copenhagen Stock Exchange, Helsinki Stock Exchange, Iceland Stock Exchange, Riga Stock Exchange, Stockholm Stock Exchange, Tallinn Stock Exchange, and NASDAQ OMX Vilnius.  It is headquartered in New York City, and its president and chief executive officer is Adena Friedman.

NEX Stock Exchange: The New Securities Stock Exchange or NEX Stock Exchange (NEX) was a stock exchange located in Podgorica, Montenegro.  The NEX Stock Exchange was founded 2001.  It was one of two principal stock exchanges in Montenegro, the other being the Montenegro Stock Exchange, also in Podgorica.  In January 2010, stockholders in NEX approved a merger with the Montenegro Stock Exchange, initially expected to take place within two to three months.  However, the two were technically merged as of 31 December 2010, with their systems jointly operating since 10 January 2011.  Thus, NEX Stock Exchange ceased to exist as a legal subject.  The merger consolidated and simplified securities trading in Montenegro.

Toronto Stock Exchange: Toronto Stock Exchange (often abbreviated as TSX) is one of the world's largest stock exchanges.  It is the ninth largest exchange in the world by market capitalization.  Based in Toronto, it is owned by and operated as a subsidiary of the TMX Group for the trading of senior equities.  A broad range of businesses from Canada and abroad are represented on the exchange.  In addition to conventional securities, the exchange lists various exchange-traded funds, split share corporations, income trusts and investment funds.  More mining and oil and gas companies are listed on Toronto Stock Exchange than any other stock exchange.

William Hill (bookmaker): William Hill plc is a bookmaker based in London, England.  It is listed on the London Stock Exchange and is a constituent of the FTSE 250 Index.

Philadelphia Stock Exchange: Philadelphia Stock Exchange (PHLX), now known as NASDAQ OMX PHLX, is the oldest stock exchange in the United States.  It is now owned by The NASDAQ OMX Group.  Founded in 1790, the exchange was originally named the Board of Brokers of Philadelphia, also referred to as the Philadelphia Board of Brokers.  In 1875, the Board of Brokers changed its name to the Philadelphia Stock Exchange.  The exchange merged with the Baltimore Stock Exchange in 1949 and was named the Philadelphia-Baltimore Stock Exchange.  It merged with the Washington Stock Exchange in 1954, becoming known as the Philadelphia-Baltimore-Washington Stock Exchange (often abbreviated as PBW).  In 1969, the exchange acquired the Pittsburgh Stock Exchange.  In 2007, PHLX was purchased by NASDAQ for $652 million.

Dundee Stock Exchange: The Dundee Stock Exchange was established in 1879.  In 1964, it merged into the Scottish Stock Exchange along with the Glasgow Stock Exchange, Edinburgh Stock Exchange, and Aberdeen Stock Exchange.  It continued to operate as a local branch until 1971, when the local exchanges closed completely.  By 1973, the Scottish Stock Exchange had merged into the London Stock Exchange.

Supporting paragraphs: Betting shop William Hill (bookmaker)
Answer: London Stock Exchange