"It may be that some of our larger companies which we've financed directly in the past ... will be listed over time. But that'll be the exception rather than the rule," founder and chief executive Oliver Samwer told a news conference.
"For us, the clear focus is on increasing the value of our operating companies. We'll only sell non-core assets, companies which don't fulfill our criteria. But it'll be the exception," Samwer said.
Rocket plans to raise up to €1.48 billion via its own IPO on October 9th. It hopes to use the cash to "fund future growth opportunities".
Incubators nurture start-ups or companies in their early years by providing them with technical and financial support. Rocket was founded by the Samwer brothers in 2007 and has produced some of Germany's best-known internet businesses, such as online retailer Zalando.
The Rocket IPO is to consist solely of new shares from a capital increase, which will be priced at between 35.50-42.50 euros apiece, valuing the company at around €6.2 billion.
Investors have from September 24 until October 7 to apply for shares, with the final price to be fixed at the end of the subscription period.
In a statement, the company said it "intends to invest in some of its younger companies, with a view to build out and maintain majority ownership positions in these selected younger companies also over the longer term". None of Rocket Internet's existing shareholders plan to sell any of their shares.
At the beginning of the month, it was announced that Zalando would be publicly listed on the DAX as well. That entry is scheduled to happen on October 1. The online retailer, which is partly owned by the Samwer Brothers, is expected to raise €750 million.