The chart below shows the average time in years between a startup’s first equity investment (usually Series A) and its sale, for companies sold in each year from 1997 to 2007. (Source is Dow Jones Venture One/E&Y study)

As you can see, companies sold in 2007 had seen almost seven years pass since their first financing. Often they were founded up to a year before they took their first financing, so they were likely eight years old when they were sold. These numbers are averages – some companies exit faster, but some exit slower as well.

This data represents M&A exits. Usually the time to exit via IPO is even longer.

Although no data is available yet for 2008, there has been virtually no venture backed IPO activity in 2008, and the number of M&A tractions is sharply down from previous years. That means that the time to liquidity is likely getting longer.

Obviously, these are backward looking metrics (2007 numbers refer to companies that were sold in 2007, not companies that were started in 2007). However, founders of companies looking to raise venture capital should be ready for the long haul. You can’t start a company and expect a quick flip.