E.g. 'to contribute existing activities to a new business venture' or 'to transfer equity/assets to the new business'.

Real-life example:
-> "Reuters (RTR.L), the information and news group, and Equant (NYSE: ENT, Paris Bourse: EQU), have agreed to form a new company to offer the world’s largest secure Internet Protocol (IP) network to the financial services industry.

[...]

Reuters will own 51% of the new company. Subject to necessary approvals, Reuters will transfer US$ 130 million of telecommunications network assets into the new entity along with over 400 staff. [...]

Equant will own 49% of the new company. Equant will contribute approximately 100 staff and US$230 million in cash to the new company. It will also provide US$125 million of other services and contribute an additional US$25 million of annual contracted revenue from its existing financial services customers."
From Reuters, see link below.

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Note added at 2002-09-05 10:35:05 (GMT) Post-grading
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Kevin, \'activiteiten\' refers here to \'business operations\' and can include any or all tangible and intangible assets required for that business. My familiarity with the field tells me that, in the given context, \'inbreng\' refers very specifically to the contribution of assets to an entity. HTH.