<a href="http://tomtunguz.com/images/stock_quote_ticker.jpg"> src="http://tomtunguz.com/images/stock_quote_ticker.jpg" width=100%/></a><p>Earlier this week, I attended the Spring YCombinator Demo Day. I've been attending for six years now. Each time, I'm impressed by the intelligence, ambition and the polish of the founders presenting companies only a few weeks or months old. As I listened to the pitches, I wondered if the types of startups founders decide to build at YC has changed over time and whether those trends are lagging or leading indicators of the market as a whole. At each Demo Day, the YC team provides investors a list of all the companies pitching and I've kept a few. To get a sense of the broader trends in YC companies, I've compared the Winter 2012 class and the Spring 2014 class by sector (consumer v. enterprise), segment (ecommerce, education, social, gaming, delivery) and by revenue model (subscription, ads, transactional).</p>