Is it the responsibility of the company's loan shareholders to sign the letter of guarantee?

Legal analysis: if the parties agree in the guarantee contract that the guarantor and the debtor shall bear joint and several liabilities for the debt, it is a joint and several liability guarantee. If the debtor of joint and several liability guarantee fails to perform the debt at the expiration of the debt performance period agreed in the main contract, the creditor may require the debtor to perform the debt, or may require the guarantor to assume the guarantee liability within the scope of its guarantee.

Legal basis: Article 388 of the Civil Code of People's Republic of China (PRC) establishes a security interest, and a security contract shall be concluded in accordance with this law and other laws. Guarantee contracts include mortgage contracts, pledge contracts and other contracts with guarantee functions. The guarantee contract is a subsidiary contract of the main creditor's rights and debts contract. If the principal creditor's rights and debts contract is invalid, the guarantee contract is invalid, unless otherwise stipulated by law. If the debtor, guarantor and creditor are at fault after the guaranty contract is confirmed to be invalid, they shall bear corresponding civil liabilities according to their faults.