An asset purchase agreement is the legal document that will govern the transfer of ownership of a business's assets from the seller to the buyer. A stock purchase agreement is a legal contract that governs the sale and purchase of shares in a company, specifying the transaction's terms and conditions.What Are Some Of The Key Considerations In A Stock Purchase Agreement? A Share Purchase Agreement is a legal contract between a buyer and a seller of company shares. This agreement transfers ownership of the corporation's shares.