15 out of 30 companies featured by Forbes did Y Combinator

Source: http://www.forbes.com/special-report/2012/30-under-30/30-under-30_tech.html and http://yclist.com/

Companies:

Branch

eBay

Peek

x Airbnb

x Pathjoy

x Stripe

Revel

x Chart.io

x MemSQL

Kaggle

x Hipmunk

x Cue

x FiveStars

x Dropbox

Box

x Funders Club

Asana

x Reddit

Clever Sense

x Zenpayroll

Learnup

Facebook

x Weebly

Intern Sushi

Radius Intelligence

x Codecademy

x Optimizely

Google

Github

Facebook