A marquee of the Arango Orillac Building lists the Mossack Fonseca law firm, the one implicated in the Panama Papers, in Panama City on April 3, 2016.

Updated on April 3 at 9:58 p.m. EST

News organizations from around the world have published investigations based on a massive trove of leaked documents they say reveal corruption and questionable business dealings of world leaders, politicians, sports stars, and others.

The German newspaper Süddeutsche Zeitung said Sunday it received encrypted internal documents from Mossack Fonseca, a Panama-based company that sells offshore shell companies around the world, from an anonymous source more than a year ago. The leak amounts to approximately 11.5 million documents—or 2.6 terabytes’ worth of data—on 214,000 shell companies spanning a period between the 1970s and 2016.

The documents, which have been dubbed the “Panama Papers,” contain mostly emails, PDF files, and photo files belonging to Mossack Fonseca, one of the largest providers of offshore financial services. They may represent the world’s biggest-ever leak of classified information.

“The data provides rare insights into a world that can only exist in the shadows,” Süddeutsche Zeitung said in its report. “It proves how a global industry led by major banks, legal firms, and asset management companies secretly manages the estates of the world’s rich and famous.”