Infineon said it would issue new shares worth a total €725 million ($1 billion), and that current shareholders would be given a place at the head of the line to buy them.
The plan calls for the issuance of 337 million new shares at €2.15 per share, a statement said.
Apollo has pledged to buy shares not taken by the current shareholders up to a total of 326 million, which would represent a stake of 30 percent minus one share in the German company.
The move confirmed a press report earlier on Friday in the Financial Times Deutschland (FTD).
The operation would be one of the biggest in a German company in several months, the newspaper said, and represents a change for Apollo, which normally acts like a hedge fund that buys an ailing company to either restructure it, sell off valuable parts, or merge it with another firm at a profit.
Infineon has suffered from a collapse of the automobile electronics component sector and is already in the process of restructuring its activities.
In the first half of its 2008/2009 fiscal year, it posted a net loss of €662 million on sales of €1.6 billion, the FTD said.