Nearly a dozen Republican and Democratic lawmakers are calling on US regulators to reject the takeover of the Chicago Stock Exchange by a coalition including several Chinese investors, writes Dave Michaels for The Wall Street Journal.

They are expected to send a letter today to the Securities and Exchange Commission, which faces an August 9 deadline to approve or veto the takeover, which is part of a plan to turn the 135-year-old exchange into a bridge between Chinese entrepreneurs and the US capital markets.