Bill Ackman wants to break Hong Kong's peg to the U.S. dollar

Bill Ackman, founder of Pershing Square Capital Management, in a suit at the 2017 SALT conference (Credit: David Paul Morris—Bloomberg via Getty Images)

Bill Ackman, founder and CEO of hedge fund Pershing Square Capital Management, is betting against the Hong Kong dollar.

The Hong Kong dollar, the currency used by the semi-autonomous Chinese city, trades within a narrow band of 7.75 and 7.85 Hong Kong dollars to the U.S. dollar, in a peg that has survived for almost 40 years. Yet a weakening Hong Kong dollar, which has forced the city's government to intervene in the currency market 40 times this year to preserve the peg, is leading some to think the peg will finally fall.