The investment bank's algorithmic trading operations placed 6,220 false orders from October 2017 to May 2018, the bourse said in a statement in Korean. Such practice may have encouraged other market participants to follow suit and buy those assets, boosting their prices, the bourse said.

A Hong Kong-based spokesman for Bank of America Merrill Lynch declined to comment.

(Reporting by Hayoung Choi and Ju-min Park in Seoul and Alun John in Hong Kong; Editing by Christopher Cushing)