They're probably putting a relatively small percentage of the company on the public market. I don't know how much of Skype is being sold, but here's an example

They're probably putting a relatively small percentage of the company on the public market. I don't know how much of Skype is being sold, but here's an example from Wikipedia: "Google's initial public offering (IPO) took place five years later on August 19, 2004. The company offered 19,605,052 shares at a price of $85 per share. Shares were sold in a unique online auction format using a system built by Morgan Stanley and Credit Suisse, underwriters for the deal. The sale of $1.67 billion gave Google a market capitalization of more than $23 billion. The vast majority of the 271 million shares remained under the control of Google, and many Google employees became instant paper millionaires. Yahoo!, a competitor of Google, also benefited because it owned 8.4 million shares of Google before the IPO took place."