Four U.S. media companies –– Gannett Co Inc., HearstCorp., McClatchy Co.and Tribune Publishing Co.–– have joined forces to form a national advertising network, Nucleus MarketingSolutions.

The companies said April 14 that Nucleus will reach more than70% of consumers in the top 30 U.S. ad markets. Digitally, the network is expectedreach 168 million unique visitors.

Former Mashable Chief Revenue Officer Seth Rogin was named CEOof Nucleus. Tony Hunter, Tribune Publishing's president of national revenue andstrategic initiatives, will serve as chairman of Nucleus.