If ownership of the central rights is unclear, the purchase lacks its foundation.
If a trademark is registered to the founder, or software was developed by external parties without an effective transfer of rights, the buyer may acquire a company without the rights to its most important asset. Clarify the chain of transfer before signing: register extracts for trademarks and patents, written transfers of rights from contractors and the treatment of employee inventions. Our post on the due diligence checklist offers context.
Only once ownership is fully documented can the appropriate warranties be negotiated in a meaningful way.