You own a business and want to buy back shares from a shareholder. A share buyback agreement can help achieve this. Or maybe you own shares in a company and want to sell them. It is wise to sketch out the terms first. Signing a share buyback agreement can help move the process forward. 2.3 Comprehensive agreement; Amendment. This Agreement, including its Preamble and Annexes, as well as other documents provided under it, constitute the complete and complete agreement and understanding between the Parties with respect to this and this Subject Matter and supersede all prior agreements and understandings in this regard. Neither this Agreement nor any provision of this Agreement may be modified, stopped, discharged or terminated unless it can be signed in writing by all parties.