Facebook Inc. (FB.O) named new leaders for some of its main divisions, including the core social network, WhatsApp and Messenger, in the biggest management reshuffling since the company’s founding.

The Menlo Park, California-based company also unveiled a new initiative to explore the use of blockchain, the decentralized ledger technology that underpins digital currencies like Bitcoin. The team dedicated to blockchain will be run by David Marcus, who formerly headed the Messenger chat app.

Facebook’s chief product officer, Chris Cox, has been promoted to oversee all of the company’s apps. Will Cathcart will become head of Facebook’s core application, the company said. The former leader of news feed, Adam Mosseri, was named head of product at photo-sharing app Instagram, replacing Kevin Weil, who will join the blockchain team.

Chris Daniels, formerly in charge of the company’s Internet.org initiative to spread connectivity in developing countries, will take charge of WhatsApp after the departure of Jan Koum, that tool’s co-founder, who announced his exit last month. The management changes were reported earlier by technology news website Recode.

Facebook is making the leadership changes after a broad review of all the company’s products and their privacy holes, sparked by the revelation in March of a data leak that exposed personal information on tens of millions of users. The social-media giant has had a stable management structure for years. Companies often shuffle executives to work on different products to bring a fresher perspective and to help the teams more easily identify problem areas.

The company also added Jeff Zients, a former Obama administration official and current chief executive officer of the Cranemere Group, to its board, according to a regulatory filing on Tuesday.