Unfortunately, the Federal Trade Commission is unlikely to get involved in this case, because the market-concentration threshold they use in hospital-merger cases is too high.

FORBES: Goal of the NYU-Continuum Hospital Mega-Merger: Raising Prices

Since then, Citadel has dramatically shrunk its position in E-Trade, nearly halving it in April 2011 to fall below the 10% threshold that allowed Griffin to take an activist stance and push for a sale or merger.

FORBES: Ken Griffin's E-Trade Move: Billionaire's Citadel To Sell As Stock Hits 52-Week High