In 2011, venture capital investors poured $28.4 billion into start-up firms, up 22% from the year earlier. However, more money went to existing portfolio companies and less into early-stage start-ups, according to the MoneyTree investment report by PricewaterhouseCoopers and the National Venture Capital Association, based on data from Thomson Reuters. Venture capitalists put $4.7 billion into biotechnology start-ups, the report found, up 22% from the year before. However, they completed only 446 deals, 9% fewer than the year before. The story was a little different for the clean technology sector. Investors put $4.3 billion into 323 cleantech deals for a 12% increase in both dollars and number of deals. In the biotech and cleantech sectors, continued investment in existing portfolio firms is “driven by the challenging exit market, which requires venture capitalists to fuel their existing portfolios longer and at greater investment levels than in the past,” says NVCA President Mark G. Heesen.