These hand signals are known as arb. I was told (when I worked for a brokerage firm) that the name stems from people involved with arbitrage needing to communic

These hand signals are known as arb. I was told (when I worked for a brokerage firm) that the name stems from people involved with arbitrage needing to communicate quickly, before the rest of the market caught on to what they were doing). https://en.wikipedia.org/wiki/Hand_signaling_(open_outcry) https://en.wikipedia.org/wiki/Hand_signaling_(open_outcry)