Andreessen Horowitz
Andreessen Horowitz (commonly abbreviated a16z, for the 16 letters between the A and Z in "Andreessen") is an American venture capital firm headquartered in Menlo Park, California. Founded in 2009 by Marc Andreessen and Ben Horowitz, it manages over $90 billion in assets across multiple funds.2 As of 2025, it ranks first among venture capital firms by assets under management.1 The firm's portfolio includes over 1,100 companies across AI, crypto, bio+health, enterprise, fintech, consumer, and defense technology.89
Founding
Marc Andreessen created the Mosaic web browser at the National Center for Supercomputing Applications (NCSA) at the University of Illinois in 1993, then co-founded Netscape. He met Ben Horowitz at Netscape, where Horowitz ran product. After AOL acquired Netscape, the two co-founded Loudcloud (later Opsware), taking it public in 2001 and selling it to HP in 2007 for $1.6 billion.1 Between 2006 and 2010, the pair angel-invested $4 million across 45 startups, including Twitter, earning them the label "super angel" investors.1
On July 6, 2009, they launched Andreessen Horowitz with a $300 million debut fund.1 The firm name became "a16z" (A plus 16 letters plus Z), a shorthand that stuck as the brand's primary identity. By November 2010, the firm had raised a second fund of $650 million, bringing assets under management to $1.2 billion within 18 months.1
Fund history and scale
a16z's fund sizes have grown by roughly an order of magnitude. The first four funds (Fund I: $300M in 2009, Fund II: $650M in 2010, Fund III: $900M in 2012, Fund IV: $1.5B in 2014) were all early-stage venture vehicles.17 The firm expanded into growth investing with a dedicated Growth fund starting in 2015, and by 2026 a16z Growth managed over $22 billion across five growth-stage funds.10
In January 2022, the firm raised $9 billion across three funds: a $2.5B venture fund, a $5B growth fund, and a $1.5B bio fund.17 In January 2026, a16z raised $15 billion across five new funds, including an American Dynamism fund ($1.176B), an Apps fund ($1.7B), and additional growth and venture vehicles.34 That single raise represented over 18% of all venture dollars raised in 2025.5
The firm's crypto arm has operated separately since 2018. a16z Crypto launched with a $300M fund, followed by Crypto Fund II ($515M, 2020), Crypto Fund III ($2.2B, 2021), and Crypto Fund IV ($4.5B, 2022). In March 2026, the crypto arm was reportedly seeking $2 billion for its fifth fund.121
Investment approach
a16z introduced what it calls the "platform model": a team of over 500 operators who provide portfolio companies with services in marketing, talent, legal, and policy, rather than relying solely on partner board seats and advice.21 Traditional venture capital firms typically employ 10 to 30 people; a16z's headcount exceeds most firms by an order of magnitude.
The firm's culture document lays out seven principles, including "we do only first class business and only in a first class way," "we believe in the future and bet the firm that way," and "we play to win."2 The "bet the firm" philosophy underpins the strategy of raising increasingly large funds and concentrating capital in categories the firm believes will dominate.6
Unlike traditional venture capital partnerships where individual partners carry deal flow, a16z operates as a single pool: deals are approved collectively, and the firm brand is primary. Eric Newcomer reported that other firms have adopted similar collective models, though critics argue the structure dilutes individual partner accountability.1516
In 2023, a16z launched Speedrun, an accelerator program based in San Francisco and Los Angeles. It initially focused on pre-seed gaming startups, offering up to $750,000 per company, and has since expanded to other categories including AI and infrastructure.1
Key people
Marc Andreessen and Ben Horowitz serve as founding general partners. Other general partners include Chris Dixon (who leads crypto investing), Martin Casado (enterprise/security), Andrew Chen (consumer/growth), and Jeff Jordan (consumer/marketplaces).1 Katherine Boyle, David Ulevitch, and Erin Price-Wright co-lead the American Dynamism fund.1 Former VMware CEO Raghu Raghuram joined as general partner in October 2025.1 In April 2025, Erik Torenberg, who had run the firm's podcast network and media operations, was named general partner following a16z's acquisition of his podcast startup.19
Margit Wennmachers, who had been operating partner since 2010, transitioned to partner emeritus in July 2025.1
Notable investments
a16z's first two investments in 2009 were Apptio and Skype.1 At the time, Skype was entangled in intellectual property litigation and faced competitive pressure from Google and Apple.1 Microsoft acquired Skype for $8.5 billion in May 2011.1
The firm's portfolio has since included many of the defining technology companies of the 2010s and 2020s:
In 2010, a16z led Okta's Series A with a $10M investment.1 In 2011, the firm invested $80M in Twitter, becoming the first venture capital firm to hold stock in all four of the then-highest-valued private social media companies: Facebook, Groupon, Twitter, and Zynga.1 The 2012 investment of $100M in GitHub returned over $1 billion when Microsoft acquired GitHub for $7.5 billion in 2018.1
Other early investments include Airbnb, Stripe, Lyft, Coinbase, Databricks, and Oculus VR.1
The firm led Roblox's $150M Series G in 2020, Figma's $50M Series D in 2020, and Clubhouse's $12M Series A (2020, $10M primary capital plus $2M for share purchases) and subsequent $100M Series B (2021).1 In 2021, a16z led OpenSea's $100M Series A at a $1.5B valuation, and invested $150M in Sky Mavis (Axie Infinity) at a $3B valuation.1
In crypto, the firm has invested in Ripple, CryptoKitties, and Yuga Labs ($450M round at $4B valuation in March 2022).1 The Kickstarter investment in December 2021 (a $100M commitment from the crypto fund that came with expectations of a blockchain pivot) backfired publicly, alienating many of the platform's users.1
a16z committed $400M in equity toward Elon Musk's acquisition of Twitter in October 2022.1 The firm has also invested in xAI, Musk's AI company.1
American Dynamism
In 2023, a16z launched the American Dynamism fund with over $500 million, focused on "companies building in the nation's interest" across defense, manufacturing, space, and robotics.120 The fund's portfolio includes Hadrian (aerospace manufacturing), Apex Space (satellites), and Castelion (hypersonic weapons).1 Its annual summit brings together startup founders, Members of Congress, and Defense Department officials.1
The fund overlaps with Peter Thiel's defense-tech thesis, particularly through general partner Katherine Boyle, who previously interned at Founders Fund and backed Anduril at General Catalyst before joining a16z.1
Crypto
a16z Crypto has operated as a separate investment arm since 2018, led by general partner Chris Dixon. When it launched, few institutional venture capital firms had dedicated blockchain investment teams.11 The arm has raised five funds totaling over $7.5 billion, with the fifth fund (targeting $2B) in market as of March 2026.12
The crypto team has published open-source tools including a gas-optimized smart contract library and an Ethereum development tutorial series, and participates in governance debates around decentralized protocols.11
Media and content
a16z was among the first venture capital firms to build a media operation that competes with technology publications for readership. The firm publishes newsletters, runs a podcast network with multiple shows, and produces essays on topics from AI to regulation, all aimed at founders and technologists rather than limited partners.15 In 2025, Erik Torenberg, Ben Horowitz, and Marc Andreessen discussed the firm's media strategy in a podcast episode titled "a16z's New Media Playbook," arguing that venture capital firms should function as media companies.16
By 2012, Business Insider called a16z "the most powerful and respected venture capital firm in Silicon Valley," citing its media savvy and deal volume.1 Eric Newcomer has reported that the firm's content operation functions primarily as a marketing channel for its portfolio companies, and that its public positions on technology regulation amount to lobbying under a different name.16
Criticism
a16z's rapid fund size growth has drawn scrutiny. Leslie Feinzaig, writing in Fast Company, argued that the firm and firms like it have moved beyond traditional venture capital into public equities, crypto tokens, and non-traditional assets, and tend to compete for obvious market leaders rather than making contrarian bets.1
The firm's $350M investment in Adam Neumann's Flow (2022), its $450M Twitter commitment (which lost $288M by September 2024),14 and the Kickstarter crypto pivot drew particular criticism.1
Marc Andreessen has said that being controversial is a competitive advantage for the firm.13 His 2023 "Techno-Optimist Manifesto" (approximately 5,000 words) argues against regulation and for technological progress as an unconditional good.2