Then, just as quickly, many of these networks withdrew from trading.
"Today, Americans face a host of new protectionist activity, including threats to withdraw from trade agreements, misguided calls for new tariffs in response to trade imbalances, and the imposition of tariffs on washing machines, solar components, and even steel and aluminum used by US manufacturers," said the letter, which was organized by the National Taxpayers Union.
After Knight's computer problems triggered runaway trading in more than 100 stocks, the firm withdrew from trading for the rest of the day.
Reed Elsevier has been withdrawing from trade magazines in recent years, selling off 45% of the RBI operation since 2008.
"The prescription of withdrawing from trade deals and focusing solely on your local market, that's the wrong medicine," he said last month.
There are questions about UBS's commitment to its new course and just how far it is willing to withdraw from risky trading activities.
At a scrap metal facility south of Pittsburgh, the presumptive Republican nominee veered yet again from conservative free-market orthodoxy as he called for the US to withdraw from free-trade deals, including Nafta, the trade agreement with Canada and Mexico.
Mr. Trump has said that as president he would "rip up" international trade deals such as the North American Free Trade Agreement, withdraw from the World Trade Organization and sharply raise the tariffs charged on goods imported from China and Mexico.
Trump withdrew from that trade deal in one of his first moves.
And he said if necessary the US would withdraw from the World Trade Organisation.
