Andreessen Horowitz (a16z)

Andreessen Horowitz, usually shortened to a16z, is the youngest of the big names on Sand Hill Road. Marc Andreessen and Ben Horowitz founded it in 2009 with a $300 million first fund. By 2026 the firm's website said it managed more than $100 billion. In between it changed how many venture firms present themselves to founders, with a large in-house support staff, its own media operation and an active policy team in Washington.

This profile is a neutral explainer for visitors and founders. It draws on the firm's website, a press release from January 2026 and reporting from Fortune, TechCrunch, Bloomberg and others. For how venture funds work in general, start with our venture capital guide.

The founders

Both founders were operators before they were investors. Marc Andreessen co-created the Mosaic web browser as a student and then cofounded Netscape, whose 1995 IPO is often seen as the start of the commercial internet boom. Ben Horowitz worked at Netscape and then ran Opsware, a software company that Hewlett-Packard bought in 2007.

From roughly 2006 to 2010 the pair invested their own money in about 45 startups, which earned them the label of super angels. In 2009 they turned that into a firm. The name a16z comes from the 16 letters between the a and the z of Andreessen Horowitz.

The platform model

Most venture firms of the 2000s were small partnerships. Each partner made investments and helped those companies personally. Andreessen Horowitz set out to work more like a talent agency. Partners would still lead deals, but a central team would serve every company in the portfolio.

• Marketing and media. The firm hired a partner-level marketing executive in 2010. Today it publishes its own articles, podcasts and newsletters.
• Talent. By 2011 it kept a database of engineers, designers and executives to help portfolio companies hire.
• Policy and legal. The firm runs a policy team and an office in Washington, D.C.

The model has been widely copied. Many firms now have operating partners, talent teams and content programs, a shift often traced back to a16z. For founders, the practical point is that a check from the firm usually comes with access to these teams.

Major deals

The firm's early years produced several investments that established its reputation. The list below follows the order in which they were made.

Airbnb and Twitter are also among its investments. More recently the firm has been an active backer of artificial intelligence companies. In 2025 it led a $2 billion seed round for Thinking Machines Lab.

Funds and specialist strategies

Instead of one main fund, Andreessen Horowitz runs a set of funds organized by sector and stage. Its website lists areas including AI, bio and health, consumer, crypto, enterprise, fintech, games, infrastructure, growth and American Dynamism. Some milestones:

• Crypto. A first crypto fund in 2018 was followed by a $515 million fund in 2020 and a $4.5 billion fund in May 2022.
• Registered investment adviser. In 2019 the firm moved to register as an investment adviser, which gave it room to invest more heavily in assets such as cryptocurrency.
• American Dynamism. Launched in 2023 with a $600 million fund to invest in defense, space, manufacturing and other areas tied to the national interest.
• Speedrun. The firm also runs Speedrun, an early-stage program listed on its website.

The January 2026 raise

On January 9, 2026, the firm announced more than $15 billion in new funds, its largest raise. The press release broke it down as follows: $6.75 billion for growth, $1.7 billion for applications, $1.7 billion for infrastructure, $1.176 billion for American Dynamism, $700 million for bio and health and $3 billion for other venture strategies.

Offices as published in 2025 and 2026

For most of its life the firm was based at 2865 Sand Hill Road in Menlo Park. In July 2022 Ben Horowitz wrote that the firm's headquarters would be "in the cloud," with staff spread across several cities and gatherings held a few times a year. It kept its Menlo Park and San Francisco offices.

The firm's office page listed seven locations in October 2026:

1. Menlo Park: 2865 Sand Hill Road, Suite 101
2. San Francisco: 180 Townsend Street
3. New York: 200 Lafayette Street
4. Washington, D.C.: 800 17th Street NW
5. Santa Monica: 1305 2nd Street
6. Seoul
7. Tokyo

In June 2024 the landlord DivcoWest announced that a16z had leased about 34,390 square feet at 2400 to 2450 Sand Hill Road, a renovated campus called The Quad, with a move planned for 2026. We could not confirm whether the move has happened. Check the firm's office page before visiting for a meeting. Our Sand Hill Road guide maps the other firms on the road.

Policy and public profile

Few venture firms are as visible in politics and public debate. Andreessen Horowitz runs a Washington office, publishes policy positions and promotes what it calls a Little Tech agenda, aimed at rules that suit startups rather than only large technology companies. Its partners write and speak widely on AI, crypto and defense. Founders do not need to share those views to raise from the firm, but it helps to know that the firm takes public positions.

Advice for founders and visitors

Because the firm is large, it has partners for many sectors and stages. Read the team pages for your area and look at recent investments before reaching out. A warm introduction from a founder or angel the partner knows is still the best route in. Cold outreach rarely works for any large firm. Our guides to pitching investors and seed and pre-seed funds explain the earlier steps.

If you are flying in, book a prebooked airport transfer for the first day and compare hotels near Sand Hill Road. A rental car makes it easier to reach both Menlo Park and San Francisco in one trip. Our getting here guide covers the airports. Our guide to moving to Palo Alto as a founder helps if a short trip turns into a longer stay.

Frequently asked questions