Can a landlord demand to see my buyer's personal financial statements before approving them?

Generally yes, and this is one of the most standard and defensible parts of a landlord's consent review. Landlords have a legitimate interest in knowing whether a proposed assignee can actually pay rent and perform the tenant's obligations for the rest of the term, and most commercial leases either expressly permit the landlord to request financial information about the assignee or leave enough discretion in the consent clause that a request for financials is treated as a reasonable step in assessing the buyer's "covenant" — their financial strength as a tenant.

This is true whether the buyer is an individual or a corporation, though what's requested may differ — corporate financial statements, personal guarantees, or bank references, for example. A refusal to provide any financial information at all can itself give the landlord a reasonable basis to withhold consent, since it leaves the landlord unable to assess the risk it's being asked to accept.

If your buyer is uncomfortable sharing certain details, it's worth discussing confidentiality protections with the landlord upfront. A Treadstone business lawyer can help negotiate what's disclosed and how it's protected.