Facebook Inc. (FB) is the largest social networking site in the world with 2.5 billion monthly active users (MAUs) as of year-end 2019.  Its namesake website and app enables people to connect with family and friends, and to share their opinions, ideas, images, and videos. Facebook also owns and operates the popular photo-sharing app Instagram as well as messaging apps Messenger and WhatsApp. Additionally, the company provides virtual-reality hardware, software, and a developer ecosystem through its Oculus business.

Facebook was founded in 2004 by Mark Zuckerberg and three fellow classmates at Harvard University at the time. Facebook went public in 2012 and has become one of the world's largest companies with a market capitalization of $507.92 billion as of April 14. Facebook earned net income of $18.5 billion on $70.7 billion of revenue during fiscal year 2019 (FY). 

Below, we'll look at the top five shareholders in Facebook based on the number of shares owned. As of this writing, four of these shareholders are investment management companies and one is Facebook co-founder and Chief Executive Officer (CEO) Mark Zuckerberg.

Mark Zuckerberg

Zuckerberg is Facebook's largest shareholder by far. As mentioned, he co-founded Facebook and has been the company's longtime chairman and CEO. At the age of 35, Zuckerberg is also ranked seventh on the Forbes World's Billionaires List with a net worth of $54.7 billion. He currently holds over 400 million shares of Facebook, comprising a market value of around $82.2 billion. Zuckerberg's holdings also give him a disproportionate share of voting rights. He controls 57.9% of the total voting shares, giving him effective control of the company.

Vanguard Group Inc.

Vanguard is one of the world's largest investment management companies with about 425 low-cost traditional funds and exchange-traded funds (ETFs). The firm has about $6.2 trillion in global assets under management (AUM). The Vanguard S&P 500 ETF (VOO) is one of the company's largest ETFs with about $130 billion in AUM. Vanguard's funds hold approximately 184.0 million shares of Facebook with a combined market value of about $37.7 billion.

BlackRock Inc.

BlackRock is one of the world's leading asset and investment management firms with approximately $6.47 trillion in AUM.  The firm offers a wide range of mutual funds, iShares ETFs and closed-end funds. The iShares Core S&P 500 ETF (IVV) is among one of BlackRock's largest ETFs with approximately $180.3 billion in AUM.  BlackRock's funds hold about 158.2 million shares of Facebook with a combined market value of $32.3 billion.

FMR LLC

FMR is one of the nation's largest financial services company and offers investment management, retirement options, brokerage, financial planning, and wealth management services. The company owns investment management firm Fidelity Investments, which has total AUM of approximately $2.5 trillion. The Fidelity MSCI Information Technology Index ETF (FTEC) is one of the firm's largest ETFs with $3.2 billion in AUM. FMR's funds hold approximately 123.6 million shares of Facebook with a combined market value of $26.1 billion.

T. Rowe Price Associates Inc.

T. Rowe Price is an investment management company offering portfolio management, equities, fixed income, asset allocation, and financial advisory services. The firm holds approximately $1.2 trillion in AUM. The T. Rowe Price Blue Chip Growth Fund (TRBCX) is one of the company's largest mutual funds with $60.2 billion in AUM. T. Rowe Price's funds hold about 107.8 million shares of Facebook totaling a combined market value of $22.1 billion.