The incident happened after a technician forgot to copy the new Retail Liquidity Program (RLP) code to one of the eight SMARS computer servers, which was Knight's automated routing system for equity orders. RLP code repurposed a flag that was formerly used to activate an old function known as 'Power Peg'. Power Peg was designed to move stock prices higher and lower in order to verify the behavior of trading algorithms in a controlled environment. Therefore, orders sent with the repurposed flag to the eighth server triggered the defective Power Peg code still present on that server [1]

> Power Peg was designed to move stock prices higher and lower in order to verify the behavior of trading algorithms in a controlled environment.

This is insane. Make one wonder, what is or isn't actually being deployed in prod in 2022.

[1] https://en.wikipedia.org/wiki/Knight_Capital_Group#2012_stoc...