In the summer of 1996, Silicon Valley venture capitalists put a few million dollars into a telecom-equipment startup called Juniper Networks. Three years later, after a few more rounds of funding and the release of its first product, Juniper enjoyed an initial public offering of shares, or IPO. At the end of its first day of trading, it was worth nearly $5 billion, and within nine months, it was worth almost 10 times that. The original venture investors, meanwhile, were able to walk away with profits of better than 10,000 percent.

Around the same time Juniper went public, Silicon Valley venture capitalists were putting money into a new networking startup, Procket Networks. This time, the initial investments were bigger, and over successive rounds of financing, Procket collected almost $300 million in venture money. Three years after it started, though, the company had still not launched a product, and in 2004 its assets were acquired by Cisco in a fire-sale deal. This time the VCs walked away with just a fraction of their original investments.