This is the same fund Fortune reported on back in January, which at the time was already said to be oversubscribed.

In a blog post announcing the close, A16Z partner and chief operating officer Scott Kupor refers to this as a “multi-stage venture capital fund,” but it’s actually two different funds that can work in parallel with one another. The main early-stage fund was capped at $1 billion, while a $500 million side fund can be used for larger opportunities (i.e., GitHub, Skype, etc.).

From Kupor’s blog post:

Perhaps most importantly, we are seeing many new companies build “full stack” startups (to use the metaphor my partner, Chris Dixon, describes here). Instead of just owning part of the stack — for example, licensing their technology for another company to embed in its end-user product — more companies today are integrating the service, end-to-end and at scale. These entrepreneurs care enough about all aspects of their product/service that they want (or need) to innovate in all the areas that touch it. These companies aren’t just controlling a better end-user experience for their customers — they’re potentially bypassing legacy constraints altogether.

The implication for venture capital in a full stack world is simple: such startups need to master multiple disciplines to fulfill their product visions. (That’s why going full stack isn’t the same thing as being fully vertically integrated; in some ways, it requires technical founders to expand their skillsets more “horizontally” into adjacent areas). To achieve this, however, will require significant amounts of equity capital to invest in multiple domains.

Andreessen Horowitz portfolio companies include Actifio, AirBNB, Box, DataGravity, Lyft and Pinterest. It also led a $75 million round last December for Oculus VR, which this week agreed to be acquired by Facebook (FB) for more than $2 billion.

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