It also set out additional steps, including tightening controls on the growing number of computerized high-frequency and algorithmic traders.
The deal talks are showcasing the rise of two markets built to favor computerized high-speed trading.
Regulators in the United States and overseas are worried that computerized high-speed trading is making market swings worse.
Regulators in the United States and overseas are cracking down on computerized high-speed trading that crowds today's stock exchanges, worried that as it spreads around the globe it is making market swings worse.
If successful, a merger would jump the combined company ahead of the Nasdaq OMX Group and put it close to the New York Stock Exchange and its electronic platform in terms of volume, as well as showcasing the rise of two markets built to favor computerized high-speed trading.
A subsidiary loser in this case is computerized, high-frequency trading.
In the age of computerized high-tech warfare, it is not just American hardware available on the black market.
This week's arrest of a British financier accused of crashing the Dow in 2010 is now raising questions about whether terrorists could wreck havoc on the global financial system using computerized, high-speed trading.
"In addition to the revenue, as I indicated, there are important policy reasons to be imposing this small fee: dampening excessive speculation, and as I said, dealing with this issue of computerized high-speed trading, which essentially skims value out of the economy for the high-speed traders, but doesn't do anything for anybody else," he said.
Van Hollen also warned of "excessive speculation" in financial markets, particularly in the form of "computerized high-speed trading," and said the existing tax code is "wired in favor of making [money] off of money instead of earning money from hard work".
