Facebook has been coy about what it is building. The team is in an office with separate key-card access so other Facebook employees cannot get in, according to two Facebook employees.

Facebook is looking at several ways to use the blockchain, the technology introduced by Bitcoin that makes it possible to keep shared records of financial transactions on several computers, rather than relying on one big central player like PayPal or Visa.

The five people who have been briefed on the Facebook team’s work said the company’s most immediate product was likely to be a coin that would be pegged to the value of traditional currencies, as Bloomberg first reported.

A digital token with a stable value would not be attractive to speculators — the main audience for cryptocurrencies so far — but it would allow consumers to hold it and pay for things without worrying about the value of the coin rising and falling.

Several other companies have recently introduced so-called stablecoins, linked to the value of the dollar. JPMorgan Chase even said it was experimenting with the concept last month.

Facebook is looking at pegging the value of its coin to a basket of different foreign currencies, rather than just the dollar, three people briefed on the plans said. Facebook could guarantee the value of the coin by backing every coin with a set number of dollars, euros and other national currencies held in Facebook bank accounts.

The company is overhauling its messaging infrastructure, which would connect three of its properties — Messenger, WhatsApp and Instagram. That integration, which could take more than a year, would extend the reach of Facebook’s digital currency across the 2.7 billion people who use one of the three apps each month.