Each market participant is recognized by the four-letter ID that appears on level II quotes. Here are some of the most popular ones: NITE, ETRF, CSTI PUMA MAXM ATDF CANT and the ones we all hate to see VFIN VNDM BMAK BKRT ARCA ASCM CDEL CFGN These 8 are rarely every up to any good. They are the dilutors selling toxic debt to your penny stock , and driving it down to triple zero.