Major League Baseball's owners on Thursday officially designated John S. Middleton as control person of the Phillies, the last step in a transition of power from David Montgomery to Middleton.

Middleton, a Phillies part-owner since 1994, has exerted a greater influence in recent years. He now is recognized by MLB as accountable for the Phillies' operation and compliance with league rules.

The team, for the first time, disclosed that Middleton owns a 48 percent stake in the Phillies. Cousins Jim and Pete Buck are the other major owners of the team.

"I am both thrilled and honored to assume this important position," Middleton, 61, said in a statement. "I'm grateful that the Buck family, Major League Baseball and the other Major League clubs have confidence in my ability to lead our franchise into the future.

"Our fans should know that the Phillies organization is committed to restoring the Phillies to its recent dominant past. We will approach the 2017 season and the years to follow with even greater intensity and determination, knowing our fans are eager to bring a championship back to Philadelphia. We intend to accomplish that goal."

Montgomery had served as the Phillies' control person since 1997. He is still involved with the club as chairman, a position that he will continue to fill.

In 1994, Middleton's family purchased a 14.7 percent stake in the Phillies for approximately $18 million, according to financial documents submitted in Montgomery County Orphans' Court. The Middletons in 2000 contributed $32.2 million to the Phillies, which raised their ownership to 26.6 percent. And, in 2001, financial records showed the Middletons purchased another 9.2 percent of interest from other partners at a cost of $19.1 million.

Middleton, in 2007, sold the family's cigar company to Altria for $2.9 billion.

It is unclear how much Middleton paid within the last decade to reach 48 percent ownership of the Phillies. Under the limited-partnership arrangement that governs the Phillies, any one partner is restricted from majority ownership. But Middleton has emerged as a public face of an ownership group that has existed in secrecy for numerous decades.

Middleton was appointed during MLB owners' annual meetings in Chicago. At the meetings, the Phillies were named 2016 recipients of the Allan H. Selig Award for Philanthropic Excellence. The award recognized the club's commitment to fighting ALS through its charitable work.