AMD spun off their manufacturing arm because they were so broke as a company they couldn't afford to stay in the business. It takes huge amounts of capital to build and upgrade fabs. Before they sold it off, AMD had over $5 billion in debt and they actually had to stop the upgrade of one of their facilities and cancel planned new ones because they couldn't secure the necessary capital to pay for them. As part of the deal to offload the fabs, AMD also offloaded over a billion dollars in debt to the new company. It didn't matter what AMD wanted, they only had one financial option which was to sell it off if they wanted the remaining company to stay afloat.