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Before Elon Musk, Peter Thiel, and Reid Hoffman were billionaire investor-entrepreneurs, they were executives at PayPal in the 1990s. They, and over a dozen other early executives at the company, including Max Levchin, David Sacks, and Keith Rabois, have become known as the PayPal Mafia, Silicon Valley’s most famous network of serial entrepreneurs and venture capitalists.

Youtube. Tesla. SpaceX. Palantir. LinkedIn. Yelp. Members of the PayPal Mafia founded them all. The have also founded venture capital firms like Founders Fund and Valar Ventures, and joined firms including Sequoia Capital, Khosla Ventures, and Greylock Partners. They have been major investors in Facebook, Uber, Lyft, Airbnb, Square, Pinterest, Stripe, and most other unicorns Silicon Valley has produced in the past two decades.

The Mafia has inspired substantial media coverage over the years, but there has not been a thorough catalog of its investments. Using data available from Crunchbase, Dow, and media reports of investments, we have compiled what we believe to be a quite comprehensive database of Mafia investment activity. Our dataset includes the investor, the company being invested in, and the date of investment; we’ve added indicator variables to show if a company receives investments from multiple Mafia members and show the investors in common.

The Mafia is all-male and has been accused of contributing to the lack of women in the technology industry, so we hand-coded a variable for whether a company had at least one female founder to gauge the percentage of investments Mafia members made in such companies.

We include personal investments made by 20 Mafia members* as well as investments made by Mafia-affiliated venture capital firms** if they are listed as “partner investments” with a Mafia member in Crunchbase. Additionally, we count investments if they are made by Mafia-affiliated VC firms into companies founded by Mafia members.

We believe this methodology is conservative, and that several Mafia members are probably responsible for more investments than we’ve captured here. For example, Reid Hoffman was probably responsible for more investments at Greylock Partners than just the ones in which he is named as a partner on Crunchbase. A more detailed explanation of our methodology can be found here.

Overall, we found 1,005 investments by Mafia members and affiliated VC firms into 646 companies over the period from 1995 to June 2018. We were able to identify founders for 642 of these 646 companies, finding 89 (14 percent) with at least one female founder; one startup had a founder who identifies as gender nonbinary.

To compare these numbers to the industry as a whole, a study using Crunchbase data found that, from 2009 to 2014, 15.5 percent of startups had at least one female founder. During the 2009-2014 period, 13 percent of startups the Mafia invested in had one such founder.

In the figure below, we show the number of investments the Mafia made over time. The group significantly increased investment activity in the mid-2000s, when it collectively made 10-40 investments per year, and then again in 2010, when it collectively made about 100 investments. Since 2010, it has collectively made about 70-130 investments per year.

In the next figure we show the number of companies each individual Mafia member has invested in (so if a Mafia member invests in the same company multiple times, that only shows up as one observation). Peter Thiel and Scott Banister, the most prolific investors, are each responsible for investments in over 100 companies. Another half dozen Mafia members have invested in several dozen companies each.

For two of the Mafia members, Dave McClure and Reid Hoffman, more than 20 percent of the companies invested in had at least one female founder. (In 2017, McClure resigned from 500 Startups after being accused of sexual harassment and admitting to “inappropriate” advances).

We were also interested in examining the strength of the ties between Mafia members, and in particular whether a company receiving an investment from one Mafia member meant the company would get an investment from a different Mafia member.

We found that 31 percent of the companies Thiel invests in also receive at least one investment from another member of the Mafia. That figure is 47 percent for Rabois, 16 percent for Hoffman, 41 percent for Levchin, 46 percent for Sacks, and 18 percent for Banister.

We found that, of the 646 companies in the dataset, 103 (16 percent) received investments from multiple Mafia members.

In the network graph below, the thickness of the line between two Mafia members represents the number of companies in which both members have made investments. The graph reveals a core network within the PayPal Mafia consisting of Sacks, Levchin, Rabois, Thiel, and Banister.

There is sometimes a temptation to think of Silicon Valley almost as an abstraction. But the PayPal Mafia network, spanning hundreds of companies and billions of dollars, is made up of actual people making observable decisions. The full dataset is here, spanning over two decades of technology history.

* Peter Thiel, Keith Rabois, Elon Musk, David Sacks, Max Levchin, Reid Hoffman, Scott Banister, Jeremy Stoppelman, Dave McClure, Andrew McCormack, Roelof Botha, Steve Chen, Jawed Karim, Ken Howery, Luke Nosek, Yishan Wong, Chad Hurley, Premal Shah, Russell Simmons, and Eric Jackson.

** Reid Hoffman is a partner at Greylock Partners; Keith Rabois is a partner at Khosla Ventures; Dave McClure was a founding partner at 500 Startups; Roelof Botha is a partner at Sequoia Capital; Peter Thiel is a cofounder and chair of the investment committee at Mithril Capital; Thiel and Andrew McCormack are cofounders of Valar Ventures and McCormack is a general partner there; Thiel, Ken Howery, and Luke Nosek are founding partners at Founders Fund; David Sacks is a founding partner at Craft Ventures; Rabois and Jawed Karim are founding partners at Y Ventures; Max Levchin is the founder of HVF Labs and SciFi VC.

Andrew Granato is an economic researcher and freelance journalist.

Scy Yoon is a programmer.

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