Although the merger of equals announced Monday between 111-year-old William Morris Agency LLC and 14-year-old Endeavor Agency LLC was preceded by six months of careful deliberation, those affected by the talent agencies' integration can expect at least another six months of pain.

"There's going to be a lot of hurt feelings, up and down the line," said Ken Sonenclar, managing director in the digital media and technology group of New York investment bank DeSilva & Phillips LLC. And that integration pain, he added, "seems likely to spawn new agencies in the near term."

Sonenclar, who not only spent college summers in WMA's celebrated mailroom but recently released a DeSilva & Phillips white paper on celebrity media titled "Lost in Transition: The Revolution in Celebrity Media," served up the perceived superiority of Endeavor's television and music departments as an example. "That may be true," he said of the perception, "but you won't get people who work in those departments at William Morris to agree."

Any disagreement seems likely to be compounded by each agency's distinct culture. "One's an established, hundred-year-plus institution; the other's still perceived as an industry upstart," said a source privy to merger negotiations. "It's remarkable to see two entities like that combine."

That, in part, is what took so long to come to terms. "Social issues are very important in deals like these," the source continued. "They take awhile for people to acclimate themselves to them and to accept them."

Ultimately, however, the privately held agencies got their top echelons to agree to join forces without a dollar changing hands and without assistance from financial advisers. Law firms were a different matter: WMA used both Munger, Tolles & Olson LLP and Hansen, Jacobson, Teller, Hoberman, Newman, Warren & Richman LLP; and Endeavor relied on Paul, Weiss, Rifkind, Wharton & Garrison LLP.

The agencies' merger of equals is consistent with Hollywood's view that, while WMA is bigger in staff and revenue, Endeavor ranks second only to Creative Artists Agency in power. Its lineup of film talent, including Matt Damon, Keira Knightley, Shia LaBeouf and Adam Sandler, is a generation younger than such WMA film stars as Mel Gibson, Steve Martin, John Travolta and Denzel Washington. WMA is also held to be weaker in TV, aside from its success with such unscripted "reality" shows as "The Biggest Loser," "Deal or No Deal" and "Dancing With the Stars."

The agreement was technically achieved through votes in favor of the merger, taken separately Monday, by WMA's 20 directors and Endeavor's 28 partners. They also agreed to name the combined entity WME Entertainment.

Much of the management structure for the combination, which awaits Justice Department approval, was mapped out as well. WMA chief executive Jim Wiatt will be chairman of WME Entertainment, whereas his president, Dave Wirtschafter, will share co-CEO status with Endeavor executives Patrick Whitesell and Ari Emanuel. The latter is the Endeavor co-founder who inspired the Ari Gold character played by Jeremy Piven on HBO's "Entourage" and the brother of White House Chief of Staff Rahm Emanuel.

Sources considered both its terms and the merger itself a function of the economic environment, where capital is scarce and the quest for savings constant. The merger's pooling of stock circumvented the need for a capital infusion, while WMA's 800 employees, including 250 agents, and Endeavor's 280 employees, including 80 agents, indicate all sorts of redundancies.

Sonenclar also saw Hollywood's ever-changing ecological system as playing a role in the merger. Despite impressive strength in recent box-office figures, power has shifted in recent years to the movie and TV studios. "It's in the hands of buyers of talent," Sonenclar explained. "That has rippled down to the tenpercenteries who sell it."

Not only would the complementary strengths of WME Entertainment restore some clout the individual agencies have lost but they could also increase the combined agency's packaging prowess. That is, by combining stables of directors, actors and writers, WME Entertainment could come up with more opportunities to sell more clients in more combinations and in more media. "That's really the upside coming out of this merger," Sonenclar said.

The banker, who's father was an agent, recognized that WMA has birthed most of its major competitors. Endeavor may have come out of International Creative Management Inc. in 1995, he said, but it was from WMA that ICM made its break in 1975.