http://mobile.chicagobusiness.com/d...-shuts-research-unit-hopes-to-sell-investment Citadel, in retreat, shuts research unit, hopes to sell investment bank By: Staff August 11, 2011 (Crainâs) â Citadel LLC founder and CEO Ken Griffin is negotiating to sell the hedge fundâs investment bank and is closing the stock-research part of his securities business, according to a report. Citadel Securities will shutter a research group led by former Lehman Bros. Holdings Inc. executive Jaine Mehring, Bloomberg News reported, citing âtwo people briefed on the move.â Other Citadel Securities employees will be let go, Bloomberg reported. A spokeswoman for Chicago-based Citadel declined to comment to the news service. Crainâs reported in November that Mr. Griffin was having a tough time building the investment bank, which had 250 employees at that point. He created Citadel Securities as a market-making entity in 2001 but expanded that side of the business in 2009 to include investment banking plus related financial security sales and trading functions.