One practice that has been associated with Microsoft, and has subsequently been investigated by the Department of Justice, is Microsoft's practice of releasing "vaporware". Vaporware is considered an unfair marketing technique - it often allows a company that already has considerable market share in one area to claim similar market share in another area without even distributing a product. The enthusiasm for the anticipated release of the product is often enough to squelch any market competition, even though there is no product to compete.

In 1995, the Court issued an inquiry concerning the issues of vaporware. Because Microsoft is not the only company to announce software long before it's actual due date, and because the announcement of a product before it's release is not illegal, it is doubtful that such an issue will be influential against Microsoft in court. Owing to these reasons, litigation on the issues of vaporware has only been slightly pursued.