[5] Marcus attended the University of Geneva for one year before dropping out initially to support his family by working at a bank[6][better source needed] and later to pursue an entrepreneurial career.

[4] In 1996 at age 23 Marcus founded GTN Telecom, a Geneva-based provider of internet access and telephone service.

In 2008,[9] he founded Zong, an offshoot of Echovox that allowed users to pay for items online directly through their mobile phone bills.

[19] In May 2018, Marcus moved from Vice President of Messaging Products to lead the experimental blockchain group at Facebook.

[20] In August 2018, Marcus left the board at Coinbase, at least in part to avoid the appearance of a conflict of interest with his work on Facebook.

[21] By February 2019, The New York Times reported that Marcus was head of a program to develop a cryptocurrency that users of WhatsApp (which is owned by Facebook) could transfer to facilitate cross-border payments.

[23] According to Clare Duffy, writing for CNN Business, "criticism from politicians, regulators and finance experts came swiftly".

[29] In May 2022, Marcus co-founded a company called Lightspark that describes itself as using the Lightning Network to "extend the capabilities of bitcoin".

[2] In October 2023, Marcus announced that Lightspark open sourced the Money Address (UMA) standard.