Many people may find it hard to understand, why wouldn't it be good to leave the shares to one's own family? If not, selling them would be fine too.
In fact, this is precisely where Fu Yuanxin's cunning and shrewdness lie.
1. Giving the shares to Qin Yu was to let him take charge and lead the Fu Clan to ensure the consortium would not fall apart and to secure its share value, because Fu Yuanxin's family owned some shares. As long as the Fu Clan remained, they could rely on these shares to live comfortably without depleting their wealth due to incompetence or foolishness.
2. Giving them to Su Wanmo was because she had a powerful background in the government, which could make Fu Yuanxin's life in prison more bearable, and also provide an extra layer of protection for the Fu Clan. Most importantly, it placed a Damoc Sword over Qin Yu's head to prevent him from becoming too powerful.