BEDMINSTER, N.J. , Jan. 13, 2020 /PRNewswire/ -- GAIN Capital Holdings, Inc. (NYSE: GCAP) ("GAIN" or "the Company") today reported certain operating metrics for the month of December 2019 . Dec-19 Nov-19 Dec-18 Sequential Change Year-over- year change Retail Segment OTC Trading Volume (1) $ 130.8