The clash was so mesmerizing that virtually all productivity on Wall Street stopped. Twitter lit up with reactions, and CNBC started trending.
Here are some of the best tweets:
"Wow. Real Housewives of Wall Street." @Ted_Newton
"Would like to see claymation death match reenactment" @JackAttax2
"Joe Peschi will play Icahn; a peroxided Jim Caviezel will be Ackman" @zerohedge
"I think Carl just needs a HUG!" @EdwardBHall
"Buffett was watching from the bath tub." @ReformedBroker
"and the trading floor goes "WOOOOAAAHHH" @AnthonyQuintano
"How does the saying go? Men will be boys?" @CNNNYSE
"Now upgraded to 'Fight of the Century'." @NYTFridge
"Going long $HLF and buying Schmuck Insurance just in case!!! :)" @SconsetCapital
I also asked people on Twitter to choose a winner: #TeamAckman or #TeamIcahn. The early tallying has Ackman beating Icahn by a three to one margin, but suddenly #TeamWapner is making a strong run. Stay tuned.
—By CNBC's Jane Wells; Follow her on Twitter: