Does my personal guarantee on a business loan survive if I later sell my shares to someone else?

Yes, typically, unless the lender specifically agrees otherwise. A personal guarantee is a separate contract between the guarantor and the lender, distinct from the shares being sold, and selling your shares to someone else does not automatically release you from an obligation you personally made to a lender who is not even a party to that share sale. The corporation may continue borrowing under the same loan long after you are no longer an owner, with your guarantee still technically in place unless it has been formally dealt with.

Getting out of a personal guarantee generally requires the lender's active cooperation, whether through a formal written release, a substitution of a new guarantor acceptable to the lender, such as the incoming buyer, or a full repayment and replacement of the underlying loan. Simply assuming the guarantee ends because you no longer own the shares is a common and risky mistake. Anyone selling shares in a business where they previously guaranteed debt should make obtaining a written release from the lender part of the closing conditions, not an afterthought handled later.