The idea of Silicon Valley “mafias” first emerged with the Oracle, Facebook, and PayPal mafias. Former Square staffers have gone on to launch startups worth nearly $40 billion cumulatively. Insider tracked 15 members of the “Square mafia” to see what they’re up to these days. Silicon Valley insiders have long been obsessed with the idea of startup “mafias.” The “PayPal mafia” was perhaps the most infamous company that spawned the founders of tech giants like YouTube, Yelp, Tesla, and LinkedIn. Facebook and Oracle also have their own mafias of former employees that have produced iconic tech companies like Salesforce, Asana, and GoodRx. Recently, attention has turned to the Jack Dorsey-founded fintech giant Square, now known as Block, whose former employees have created and led startups cumulatively worth nearly $40 billion, based on private valuations from PitchBook and enterprise values for public companies, from this non -exhaustive list.”Jack and I initially hired aspiring entrepreneurs — we were intentionally looking for people who had aspirations of starting their own company, and we wanted those potential founders to help us build Square,” said Keith Rabois, the company’s former COO, who is now a general partner at Founders Fund and the CEO of Opendoor — which is featured on this list. He added that as Square grew, the company put programming in place designed to teach employees how to be founders, and the startup’s highest achievers were paired with external mentors to help them develop skills and learn more about building companies.”I always told employees that it’s my job to make your job at Square so challenging ing and fulfilling that you keep deferring leaving to start your own company,” Rabois said. “If your role isn’t expanding in intellectually challenging ways, I’m perfectly comfortable for you to then depart.” Many of these former Square staffers have carried over certain core values from the fintech to their current ventures, such as focusing on the customer, utilizing technology to uplift businesses, and emphasizing consistently strong execution, they told Insider. “Our purpose at Nextdoor is to cultivate a kinder world where everyone has a neighborhood they can rely on, and like Square, we see how empowering communities and small businesses at a grassroots level can really change how those neighborhoods survive and thrive,” Sarah Friar, the Nextdoor CEO and the former Square CFO, said. Some said that Square gave them a business model to emulate for their own startups. Others said they met their cofounders or early employees while at the company. Insider tracked 15 ex-Square employees in their current ventures, ranging from launching multibillion-dollar public companies to running high-profile VC firms. Here’s what they’re up to now. The rent-to-own startup Divvy Homes, cofounded by the former Square product manager and financing lead Adena Hefets, declined to be included on this list.