Effective January 3, Alan Armstrong has taken the helm of integrated, gas-focused The Williams Cos. Inc., Tulsa, Okla., (NYSE: WMB) and its general partner and wholly owned subsidiary Williams Partners GP LLC. Armstrong succeeds retired CEO Steve Malcolm. Concurrent with his new role as CEO, Armstrong has joined the parent company's board and is also the general partner's new chairman.

Having held the position of chairman and CEO since 2002, Malcolm retired from Williams at the end of 2010. He was formerly chairman and CEO of Williams Partners GP LLC, a wholly owned subsidiary of Williams and the general partner of Williams Partners LP (NYSE: WPZ), since its formation in 2005.

Prior to becoming CEO, Armstrong was senior vice president and president of Williams' midstream business since 2002. He joined Williams in 1986. Armstrong was also a director of Williams Partners GP and led its midstream business since its inception in 2005. Armstrong is currently president of the Gas Processor's Association and is on the board of the Natural Gas Supply Association. He also chairs the board of visitors at the University of Oklahoma's College of Engineering.

Alan Armstrong: CEO, Williams.

In October 2010, Williams' board appointed Frank MacInnis to succeed Malcolm as chairman of Williams. A director of the company since 1998, MacInnis chairs the board's nominating and governance committee and is a member of its compensation committee. He is also the first non-executive to become chairman of Williams' board. MacInnis was CEO of EMCOR Group Inc. (NYSE: EME) for more than 16 years until he stepped down in May 2010.

Malcolm's retirement brings to a close a career at Williams that began in 1984, when he joined as director, business development. President and chief operating officer since September 2001, Malcolm was named CEO in January 2002, and was then elected chairman of the board in May that same year.

According to W.R. Howell, the lead director of Williams' board, Malcolm took the reins at Williams "in the midst of an extraordinarily challenging period in this 102-year-old company's history."

"Under his leadership, Williams honed its focus on natural gas businesses and earned a track record of both growth and a level of financial discipline that allowed the company to recapture and sustain its investment-grade status," he says. As well, Malcolm led the creation and growth of Williams Partners, which is currently one of the largest master limited partnerships, Howell adds.

Williams focuses on E&P, midstream gathering and processing and interstate gas transportation primarily in the Rockies, Gulf Coast, Pacific Northwest, Eastern Seaboard and Pennsylvania Marcellus shale. The company holds a 77% ownership interest in its midstream interstate gas pipeline and midstream assets in MLP Williams Partners, which operates most of its midstream assets.