A crush of traders, photographers and reporters huddled around the Barclays post on the NYSE's floor.
Barclays' Glenn Carell, the designated market maker for Twitter's initial public offering, is barking out buy orders for the soon-to-debut stock.
It's part of the price discovery process as traders try to narrow the spread to find Twitter's opening price when it begins trading on the stock market.
Traders are yelling back and forth ("Yo! What did he say?") -- it's a bit of commotion that's unusual as computers have largely replaced floor traders. Indeed, high-speed trading has helped transform exchange floors into glorified television sets.
"It's not as much fun" these days, said floor trader Robert Oswald, as he punched in orders on his handheld computer. "Any time you get to yell and throw paper is pretty fun."
Twitter executives and exchange officials are in the Barclays post, waiting for the "book" to close for Twitter to begin its life as public company.
The spread on the potential opening price had narrowed to $45 and $47 as of an hour after the opening bell, then changed to $45.50 and $46.50.
Twitter began trading at $45.10, with the stock quickly heading up.
It's unusual for newly public stocks to take this long to open on the stock market, but not for hot IPOs with enormous volume.