http://www.bloomberg.com/news/artic...ls-brace-for-continent-wide-limits-on-trading Europe is imposing limits out of concern that the rise of dark pools -- whose order books are kept secret -- is making prices on public exchanges less accurate. Large investors favor them because they can find privacy to trade big blocks of shares, in theory getting better prices because it’s tougher to sniff out their strategies in the dark. “The thresholds are still too large, particularly for large-cap stocks,” said Rob Boardman, chief executive officer for Europe of Investment Technology Group Inc., which operates a dark pool. “If you try to send an order in these sizes to the lit market, you could have significant market impact.” Under the rules, private stock-trading platforms won’t be able to trade a given company’s stock for six months if a total of 8 percent of its volume is traded on dark pools during the previous 12 months. Additionally, any dark pool that handles 4 percent of a given stock for a year will then be stopped from trading it for six months.