How should deal teams protect documents during M&A due diligence?

Deal teams should protect documents during M&A due diligence by controlling who can access sensitive files, how those files are shared, and what happens after access is no longer needed. In most deals, the risk is not only a cyberattack. It is also accidental exposure, broad access, unmanaged external sharing, or confidential information staying available after the review period ends. 

A good starting point is to separate due diligence content from normal business collaboration spaces. Financial records, HR files, legal documents, customer contracts, security reports, and intellectual property should not be stored in general Teams channels or broadly shared SharePoint sites. Create a controlled workspace with limited owners, clear permissions, and approved external users only. 

Access should be based on the role of each person in the transaction. Internal executives, legal counsel, finance teams, outside advisors, auditors, and buyer-side reviewers usually do not need the same level of access. Microsoft Entra cross-tenant access settings can help organizations manage inbound and outbound collaboration with users from other Microsoft Entra organizations. (Microsoft Learn) 

Documents should also be classified and protected. Microsoft Purview sensitivity labels can help classify and protect organizational data, including documents and emails. (Microsoft Learn) For highly confidential deal documents, labels, DLP policies, retention settings, and audit logs should be reviewed before sharing begins. 

Deal teams should avoid anonymous links wherever possible. External sharing should be limited to named users, with expiration dates, MFA, and periodic access reviews. SharePoint and OneDrive support external sharing, but the settings must be configured carefully. (Microsoft Learn) 

In short, deal teams should protect M&A documents by using controlled workspaces, role-based access, sensitivity labels, external sharing limits, audit logs, and a clear offboarding process after due diligence ends.