The Dewey & LeBoeuf holdouts are finally headed toward the exits.

Morton Pierce, the longtime chair of predecessor firm Dewey Ballantine and a mergers and acquisitions heavyweight, has left the firm and is joining the partnership at White & Case today.

Pierce, 62, who said he was making one of his last phone calls from his longtime firm, said he is leaving because of “what’s happening at the firm that you can read about in the papers and the blogs daily.”

“You’re reading about what’s happening and so everyone is looking for stability in their lives,” he said.

“I’ve had 26 great years at Dewey. It’s been a great place for me,” Pierce said. “It’s a very sad day for me to leave the firm and to leave behind a lot of great people.”

He said he had “no idea” what will happen to Dewey and referred questions to the firm chairman’s office.

Pierce has led Dewey’s once-150-lawyer M&A practice as well as been a member of the firm’s executive committee, and co-vice chair of the firm. Pierce has repeatedly, however, said that he has no real management role at Dewey, despite the titles. Pierce led Dewey Ballantine through the firm”s 2007 merger with LeBoeuf, Lamb, Greene & MacRae, when LeBoeuf chair Steven Davis took over the combined firm.

A graduate of Yale University and University of Pennsylvania Law School, Pierce was among the highest paid Dewey partners and has an estimated $60 million book of business. As part of the merger, according to two former partners, including a former member of management, Pierce’s contract guaranteed him $5-6 million a year in compensation and that he be paid ahead of all other partners.

Pierce has longstanding ties to Walt Disney; Sony Corporation, and many others, but it is unclear if he will bring his clients over to his next firm. His relationship with Disney dates to his days at Dewey Ballantine, when Disney turned to the firm for counsel on major M&A deals like the company’s $19 billion purchase of Capital Cities/ABC in 1996 and the $5.3 billion buy of Fox Family Worldwide in 2001.

The current crisis does not appear to have slowed his work. Sony turned to Pierce last November in its $2.2 billion acquisition of EMI Music Publishing. And in February, Pierce advised Mexico’s Genomma on an $834 million offer for home cleaning products company Prestige Brands.

But he has seen some of his closest colleagues depart for other firms. In January, for instance, Joseph Cosentino and Ivan Presant moved to Clifford Chance; the two had worked closely since the merger on Pierce-led deals like Talbots in its defense last summer of a private equity suitor Sycamore Partners last summer; Walt Disney in its $4 billion acquisition of Marvel Entertainment and eBay in its $1.9 billion sale of Skype in 2009; and King Pharmaceutical’s hostile $1.6 billion takeover of Alpharma in 2008.

Pierce’s departure brings the number of partner losses at Dewey to more than 90 since the start of the year, the latest coming from a trio of London partner headed to Morgan, Lewis & Bockius. Firm management sent a memo to its partners late Monday telling them they have no obligation to stay at the firm, and mentioned that even members of the firm’s executive committee and office of the chairman were considering future options.

|@ New York Law Journal reporter Christine Simmons and American Lawyer reporters Brian Baxter and Julie Triedman contributed reporting.