Follow-on Offerings (FOO), are private stock sales made by companies that have just gone public. Your portfolio is full of guys like me, who behave badly after their IPO, but only when we're in a good place. And then there are the companies with perfect business models who don't need to find ways to get more capital; they already have no problem getting cash from investors and institutions.Follow-on offerings refer to stock issuances of companies following their initial public offering. Follow-on offerings can be un-diluted or partially dilutive (or abbreviated "PDO" for the former and "DDO" for the latter). The dilution is based on the number of shares that might have been issued in the IPO.The term "follow-on offering" has become a buzzword in the financial world over the past few years. Stock market experts and analysts have been predicting FPOs will become more common (such as with companies such as Facebook and Groupon).For those of you who are new to this, a follow-on offering (FPO) is when a company issues additional stock after an IPO. There are two types of FPOs: diluted and non-diluted. A diluted follow-on offering happens after the initial IPO. This can lower the earnings per share (EPS) since the company issued additional shares on top of their original offering price.