The first news stories on the Panama Papers were published, revealing that shell corporations represented by the Panamanian law firm Mossack Fonseca had been used for illegal purposes.

The Panama Papers are 11.5 million leaked documents published beginning April 3, 2016. The papers detail financial and attorney–client information for more than 214,488 offshore entities. These documents, some dating back to the 1970s, were created by, and taken from, the former Panamanian offshore law firm and corporate service provider Mossack Fonseca, and compiled with similar leaks into a searchable database.

A shell corporation is a company or corporation with no significant assets or operations often formed to obtain financing before beginning business. Shell companies were primarily vehicles for lawfully hiding the identity of their beneficial owners, and this is still the defining feature of shell companies due to the loopholes in the global corporate transparency initiatives. It may hold passive investments or be the registered owner of assets, such as intellectual property, or ships. Shell companies may be registered to the address of a company that provides a service setting up shell companies, and which may act as the agent for receipt of legal correspondence. The company may serve as a vehicle for business transactions without itself having any significant assets or operations.

Mossack Fonseca & Co. was a Panamanian law firm and corporate service provider. At one time it was the world's fourth-largest provider of offshore financial services. From its establishment in 1977 until the publication of the Panama Papers in April 2016, the company remained mostly obscured from public attention, even though it was a major firm in the global offshore industry and acted for approximately 300,000 companies. Prior to its dissolution, the company employed roughly 600 staff members spread across 42 countries.