 Citigroup Inc. increased its position in Atrion Co. NASDAQ:ATRI by 83.9 in the 4th quarter, HoldingsChannel reports. The fund owned 958 shares of the medical instruments suppliers stock after buying an additional 437 shares during the quarter. Citigroup Inc.s holdings in Atrion were worth 720,000 as of its most recent filing with the Securities and ... 