When one party assigns all or part of his investment to a third party, the other party has pre-emptive right. 合营一方转让其全部或者部分股权时,合营他方有优先购买权。
The preemption right in co-ownership is a expectant right as well as a formative right which means it's up to the co-owner's own willing to change the legal relationship. 共有关系中优先购买权是一种待实现的权利即期待权,同时也是附条件的以自己单方意思表示就能使法律关系发生变化的形成权。