If the business owned the building (i.e. the business was an LLC or corporation--presumably a corporation, since you use the term "shareholder"--and the LLC or corporation was the owner) and he is the majority shareholder, then yes, he can make the decision to sell the building without you; the majority shareholder can direct the sale, use, disposition, etc. of corporate assets. If you remain a minority shareholder, if the proceeds of the sale are distributed to the shareholders, you must get the appropriate share.If the building was owned by you and him as co-owners in your own names, then he cannot sell it without you: one co-owner may not unilaterally (on his own) sue jointly owned property.It would be a good idea for you to consult with an attorney to make sure your interests are fully protected here.