But Altman makes this clear: The fund will be focused on those specifically in the Y Combinator portfolio, not outside. So if you’re looking for funding, you’ll have to graduate from the accelerator. Y Combinator will also not lead seed or traditional series A rounds. What is likely to happen is that instead of hedging their bets in the early stages by giving a small seed investment to dozens of companies, this new investment vehicle is more serious about picking winners — those that will be the next Airbnb, Dropbox, and Stripe.

http://venturebeat.com/2015/10/15/y-combinator-raises-700m-to-keep-funding-yc-startups-as-they-mature/