David Muir Named Co-Anchor of "20/20″ ABC News President Ben Sherwood made an announcement today about the on-air team at "20/20″ - See his email to the news division below: I'm writing with important news about our on-air team at "20/20." Starting today David Muir will join Elizabeth Vargas as co-anchor while continuing to anchor "World News" on the weekends and to substitute for Diane and report during the week. For the last two years David has appeared on air more often than any correspondent at any news division, reporting from Tahrir Square to Fukushima to Tucson to Aurora. David has been an authoritative presence at the anchor desk, most recently anchoring nearly five hours straight as we learned of the horrible events unfolding in Newtown. Last year he logged thousands of hours on the road while covering the Romney campaign, crisscrossing the country numerous times. His interviews with Governor Romney often made headlines far beyond ABC News. In 2011, he was the first American journalist to report from Mogadishu, where he covered the devastating famine in East Africa, taking viewers on a harrowing 100-mile trek from Somalia to food and freedom at refugee camps in Kenya. That effort earned him a prestigious Murrow award. David has a true talent for connecting with our viewers, and his award-winning reporting will now find a new home at "20/20." I'm delighted he's bringing his ample storytelling skills to Friday nights in primetime, where Elizabeth and the team are delivering the biggest audience in years. I'm also writing to let you know that Chris Cuomo is leaving ABC News. CNN has issued a statement about his new role. For the last 14 years Chris has been an important voice on every program and platform at ABC News. He covered natural disasters and the terrible aftermath of mass shootings at Ft. Hood, Virginia Tech and Sandy Hook Elementary. He also reported on America's fight in Afghanistan and Iraq from the front lines. Chris's unforgettable GMA profile of 12-year-old poet Mattie Stepanek was recognized with an Emmy award. Some see injustice in the world and are simply outraged; Chris simply demands answers. Chris challenged the parole officials who failed to find Jaycee Dugard despite so many visits to that house of horror. He brought us the riveting story of Hero #1 from the Jerry Sandusky case, memorably chasing down high school officials in a parking lot. And he asked Dahrun Ravi point blank if he was responsible for the death of his Rutgers roommate Tyler Clementi. Chris has been a unique voice at the anchor desk and a valued colleague and friend. We'll miss his energy, commitment and humor and we wish him the very best in this new venture. Please join me in thanking Chris and congratulating David.