2ND UPDATE adds new details: The exit of the braintrust of CAA’s comedy department agents to UTA is not only the most seismic mass movement from one agency to another in recent memory, it has put some of the biggest Hollywood stars in play and possibly on the move. And it may not be over, with speculation swirling that more CAA agents may be following suit. There are several agent names floated out there as potentially moving to UTA though that has not happened, at least not yet.

While at CAA, Jason Heyman, Martin Lesak, Greg Cavic, Gregory McKnight and Nick Nuciforo, who just joined UTA this morning, repped clients that include Chris Pratt, Will Ferrell, Melissa McCarthy, Vin Diesel, Jim Parsons, Jason Bateman, Zach Galifianakis, Jimmy Fallon, Seth Meyers, Robert Ben Garant, Rawson Marshall Thurber, Garry Shandling and Danny McBride.

While many agents have left or have been eased out of CAA only to see their clients stay, that hasn’t always been the case. Most recently, Dan Aloni exited and went to WME, and took his entire list with him including director Christopher Nolan. When Warren Zavala left CAA for WME, his list also followed, including Joseph Gordon-Levitt. UTA’s press release on the CAA agent hires says that the quintet’s “clients are expected to follow them to UTA,” though no client names are listed.

This day could turn out to be like that scene early in Jerry Maguire, where Tom Cruise’s super agent character spent the day racing against his former cohorts to try keeping his clients after being fired from Sports Management International. Add to that the WME agents who’ll try to be opportunistic and look to poach, and well, don’t take offense if your top agent is slow returning your call today. The big questions will be: Why did so many agents leave at once and how long has this been percolating? Has the CAA culture changed that much, since it became majority backed by TPG? And, will more agents exit?

This development gives UTA the chance to have its best comedy stronghold in film, TV and touring since back before UTA partners Jason Heyman and Martin Lesak (among the five new UTA hires) left in 2005 in another shocker to join CAA, taking Ferrell and others with them. Heyman and Lesak spent the past years helping form a comedy group at CAA. Now it is UTA that has been opportunistic, placing CAA on its heels by creating a large hole with the exits of those who helped build its dominant comedy business. I’ve already heard some call this the largest exit of talent since Ari Emanuel and a few ICM agents loaded files into a station wagon and started Endeavor. One difference is that those guys left with mid-level TV clients mostly, and didn’t potentially bring stars as big as the ones that might change agency addresses shortly after today’s bombshell move. Stay tuned.

UPDATE: UTA has confirmed its windfall of CAA agents. See the release below.

PREVIOUS, EXCLUSIVE, 10:37 AM PT: In one of the bigger mass exits of significant agents in years, five senior agents who’ve run the comedy group at CAA for film, TV and comedy touring have left that agency. They have landed at UTA. Those agents include Jason Heyman, Gregory McKnight, Martin Lesak, Greg Cavic and Nick Nuciforo, the head of the agency’s comedy touring division. This will have ramifications that include client movement. DEVELOPING

Here’s the official word from UTA:

Former CAA agents Jason Heyman, Martin Lesak, Gregory McKnight, Greg Cavic and Nick Nuciforo have joined UTA as agents and partners of the agency, it was announced today. Heyman will also serve as a Special Advisor to the Board of Directors of UTA, and Nuciforo will head the agency’s comedy touring division.

As a group, Heyman, Lesak, McKnight, Cavic and Nuciforo represent leading artists working in film, television, digital and comedy touring. Their clients are expected to follow them to UTA.

“Jason, Marty, Gregory, Greg and Nick are among the most respected agents in our industry,” said UTA managing directors David Kramer, Jay Sures and Jeremy Zimmer, CEO, in a joint statement. “We’re excited to have them join UTA’s collaborative culture, and we know that they and their clients will thrive here.”

Heyman and Lesak are returning to UTA where they were previously partners.

The group joins the UTA partnership which recently promoted eight additional agents to partner. UTA has nearly 200 agents working in Beverly Hills and New York.