One theory is that it was part of a pump and dump stock operation.

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With the end of Operation Twist, the Fed has largely depleted its stock of short-term Treasuries.

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In New York, City "operation Atlas" has deployed armed police at key locations like the Stock Market and Pennsylvania Station.

BBC: US prepares for terror attacks

It has a small options operation that it inherited in its merger with Archipelago Holdings, which had acquired the Pacific Stock Exchange last year.

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