They do and very frequently. A big chunk of intraday trading of currencies and bonds is done by bots that connect through APIs to brokers like interactive broke

They do and very frequently. A big chunk of intraday trading of currencies and bonds is done by bots that connect through APIs to brokers like interactive brokers. There a some mutual fund companies that have "black box" investment managers, which are computer programs that manage whole portfolios and trade their institutional accounts at investment banks. Program trading on the NYSE has been active since the 1980s.