Why do asset owners sell their asset managers nowadays?

Captive asset managers are being sold. For example, NN sold NNIP to Goldman Sachs, and Athora Netherlands sold Actiam to Cardano. Does a push drive these transactions, or is it a pull factor? It seems the initiative of the transactions originates from the seller. What is the rationale behind these transactions?

Most financial institutions no longer manage the restaurant and cleaning themselves, and these activities are now usually provided by a third party. The idea is that financial institutions can better outsource non-core activities. Is this also applicable for asset management? Likely so.

Reasons often mentioned are scale, expertise, focus, and management attention, and the same goes for large pieces of IT development. The big question is whether the same arguments also apply to asset management, and if so, what is the right time to act and sell the asset manager you own.

Is the real motivation disclosed, or is there still something hidden because it will harm the seller’s power? What could be the unknown driver? Underperformance, high costs, additional capital requirements.