Marc Andreessen, co-founder of Netscape, is forming a new venture capital firm aimed at funding enterprise startups.

The new firm, Andreessen Horowitz, was formed with his friend and collaborator Ben Horowitz, and is sitting on an investment fund of around $500m (£309m). The company will be looking to invest between $50,000 (£30,000) and $5m (£3.9m) in new firms.

"Above all else, we are looking for the brilliant and motivated entrepreneur or entrepreneurial team with a clear vision of what they want to build and how they will create or attack a big market," said Andreessen in a blog post.

"We cannot substitute for entrepreneurial vision and drive, but we can help such entrepreneurs build great companies around their ideas."

The pair will be looking for firms that want to operate in cloud computing, software-as-a-service, mobile software and services, software-powered consumer electronics, infrastructure and applications software, networking, storage, databases and other back-end systems.

The company is not interested in green technology, nanotechnology, life sciences research or energy technology, since they have no experience in these areas.

Andreessen said that the firm would be "hugely in favour" of companies with a strong chief technologist, and those where the chief executive was also the founder. While he recognised that founders can make bad chief executives, most technology companies were best run by their founder.

"We are primarily, but not entirely, focused on investing in Silicon Valley firms. We do not think it is an accident that Google is in Mountain View, Facebook is in Palo Alto and Twitter is in San Francisco," he said.

"We also think that venture capital is a high-touch activity that lends itself to geographic proximity, and our only office will be in Silicon Valley. That said, we will happily invest in exceptional companies wherever they are."