Stronger Controls, Fewer Risks: How Microsoft 365’s Latest Update Protects Your Financial Data

If you work in financial services or run a hedge fund, you already know that collaboration with auditors, legal teams and specialist third parties is part of daily life. What’s less visible is how often sensitive information is exposed because of misconfigured sharing settings in Microsoft 365.

Microsoft has recently released new controls that give firms far more influence over how external users access files, chats and workspaces. These updates matter, especially in regulated environments where a single sharing mistake can lead to a serious data incident.

At Maple, we're already helping clients assess and tighten their external sharing posture so they can collaborate with confidence.

 

Why External Sharing Needs Attention

Highly sensitive data

Financial documents, investor information, legal files and trade details are exactly the sort of content attackers look for. If an external user ends up with broader access than intended, the fallout can be significant.

Sharing mistakes are common

Employees often assume a simple “share with an auditor” action is harmless. In reality, choosing the wrong link type or granting broad access can create long-lasting exposure.

Regulatory expectations

Regulators assume you know who has access to your data and why. If guest accounts or external users linger after a project ends, that’s a compliance issue waiting to happen.

 

What’s New in Microsoft 365

Automatic file sharing in external Teams chats

Microsoft Teams now supports smoother file and Loop component sharing with external users in 1:1 and group chats. This helps collaboration, but it also means your policies need to be well-defined so files aren’t shared more widely than intended. Admins can control or disable this behaviour through messaging policies.

Entra B2B guest lifecycle improvements

Microsoft has shifted away from anonymous links and one-time passcode sharing. Using Entra B2B, external users must now authenticate as managed guest accounts. This gives you proper auditing, clearer ownership and stronger identity controls.

Controlled sharing for eDiscovery

Microsoft Purview eDiscovery now allows organisations to share export packages with external legal teams without adding them to the tenant. The access is time-limited and can be tightly managed.

These changes give firms better oversight, but only if policies and governance are in place.

For background reading, Microsoft’s documentation is a good starting point:
https://learn.microsoft.com/microsoft-365/solutions/secure-external-sharing
https://learn.microsoft.com/microsoft-365/compliance/
https://learn.microsoft.com/microsoft-365/enterprise/microsoft-entra-b2b

 

How to Strengthen Guest Access

Enforce strong authentication for guests

Use Conditional Access policies to require MFA before any external user can access your environment. This closes one of the most common gaps in external collaboration.

Limit sharing permissions

Set SharePoint and OneDrive policies so staff can only share files with authenticated guests, not “anyone with the link”. Apply link expiration so access naturally closes unless renewed.

Regularly review guest accounts

Guest users should not live indefinitely. Introduce automatic expiry and scheduled access reviews so old accounts are retired.

Use sensitivity labels

Microsoft Purview sensitivity labels allow you to choose whether a site, team or group can host external users. This helps you ring-fence areas that contain high-risk financial data.

Monitor activity

Audit logs, access reports and alerting rules are essential. If an external user downloads unusual volumes of data or accesses content outside their role, you need to know straight away.

 

How MapleTech Helps Financial Firms Stay Secure

Working with financial organisations is our core focus. We understand the regulatory, operational and client-driven pressures you face. Our support covers:

• Policy design and implementation: We help define practical but strict external sharing rules that suit your business operations.

• Guest lifecycle governance: From invitation workflows to automated expiry, we make sure every external user is controlled.

• Compliance alignment: We use Microsoft Purview and native auditing tools so you can clearly evidence control to auditors, investors and regulators.

• Ongoing monitoring: Security isn’t “set and forget”. We continually review configurations as Microsoft releases new features.

 

The Bottom Line

Misconfigured external sharing is one of the most common causes of data exposure in Microsoft 365. With financial data, the stakes couldn’t be higher.

Microsoft’s new controls are a big step forward, but they only deliver value when paired with the right governance and technical setup. That’s where we come in.

If you’d like Maple to review your current external sharing and guest access settings, we can run a short assessment and guide you through the changes that will have the greatest impact. Get in touch with us!