Brown Advisory Security Incident and Data Breach Notification

Important Security Notification We are writing to provide you with a further update on the recent security incident involving unauthorized access to certain of our systems. Upon discovering the issue, we engaged leading cybersecurity experts, initiated an investigation to understand the scope and nature of the incident, and have taken steps to contain it. This notice provides information concerning the incident and the service we are offering to help you protect yourself. What Happened? On January 21st 2026, Brown Advisory discovered a security incident involving unauthorized access by a recognized threat actor to certain of our systems. Upon learning of the issue, we promptly engaged leading cybersecurity experts and, with their assistance, have been conducting an investigation into the matter. We also notified law enforcement. The investigation indicated that an unauthorized threat actor accessed certain personal data through a limited number of applications for a limited period of time. Importantly, this incident did not involve an attack that compromised the security or functioning of our internal systems. Based on the investigation, there was no evidence the criminal actor had access to transactions, trading, or client investments. What Information Was Involved? Depending on your interactions with us, the incident may have impacted certain of your personal information, for example, your name, phone number, email address, address, Social Security number, driver’s license image, passport image, or financial account numbers. qppssppprspppqpqsprssqrrqqprsrppppsrsqrqqsqrsrpqsqqppssppsssqrsqpANYTOWN, ST 12345-6789123 ANY STREETAPT ABCSAMPLE A SAMPLE - L01 US S GEN 1BP6163-L01-0000001 P001 T00001 ********SCH 5-DIGIT 123450000001 Return Mail Processing PO Box 589Claysburg, PA 16625-0589 ENGAGE#  March ,  Dear Sample A. Sample,

What We Are Doing We took numerous actions consistent with our forensic provider’s current recommendations to fully evict the threat actor from the environment, including resetting passwords and session tokens for the known compromised account. We are also offering you 24 months of identity protection services and credit monitoring from a leading identity monitoring services company, Experian, at no charge. These services help detect possible misuse of your personal information and provide you with identity protection support focused on identification and resolution of identity theft. For instructions on completing the enrollment process for these complementary protection services, please refer to the instructions below. What You Can Do Please review the Additional Information at the end of this letter for more information. For More Information If you have any further questions regarding this incident, please contact your Brown Advisory team. We are very sorry for any concern or inconvenience that this incident may cause you. Sincerely, Edward Chadwyck-Healey Global COO, Private Client, Endowments and Foundations Business INSTRUCTIONS FOR EXPERIAN IDENTITYWORKS To help protect your identity, we are offering complimentary access to Experian IdentityWorksSM for twenty- four (24) months. If you believe there was fraudulent use of your information as a result of this incident and would like to discuss how you may be able to resolve those issues, please reach out to an Experian agent. If, after discussing your situation with an agent, it is determined that identity restoration support is needed then an Experian Identity Restoration agent is available to work with you to investigate and resolve each incident of fraud that occurred from the date of the incident (including, as appropriate, helping you with contacting credit grantors to dispute charges and close accounts; assisting you in placing a freeze on your credit file with the three major credit bureaus; and assisting you with contacting government agencies to help restore your identity to its proper condition). Please note that Identity Restoration is available to you for 24 months from the date of this letter and does not require any action on your part at this time. The Terms and Conditions for this offer are located at www.ExperianIDWorks.com/restoration. ENGAGE#

While identity restoration assistance is immediately available to you, we also encourage you to activate the fraud detection tools available through Experian IdentityWorks as a complimentary 24-month membership. This product provides you with superior identity detection and resolution of identity theft. To start monitoring your personal information, please follow the steps below: • Ensure that you enroll by June 30, 2026 (Your code will not work after this date.) • Visit the Experian IdentityWorks website to enroll: www.experianidworks.com/1Bplus • Provide your activation code: ADDITIONAL DETAILS REGARDING YOUR 24-MONTH EXPERIAN IDENTITYWORKS MEMBERSHIP A credit card is not required for enrollment in Experian IdentityWorks. You can contact Experian immediately regarding any fraud issues, and have access to the following features once you enroll in Experian IdentityWorks: • Experian credit report at signup: See what information is associated with your credit file. Daily credit reports are available for online members only.* • Credit Monitoring: Actively monitors Experian file for indicators of fraud. • Identity Restoration: Identity Restoration specialists are immediately available to help you address credit and non-credit related fraud. • Experian IdentityWorks ExtendCARE TM: You receive the same high-level of Identity Restoration support even after your Experian IdentityWorks membership has expired. • $1 Million Identity Theft Insurance*: Provides coverage for certain costs and unauthorized electronic fund transfers. * Offline members will be eligible to call for additional reports quarterly after enrolling. * The Identity Theft Insurance is underwritten and administered by American Bankers Insurance Company of Florida, an Assurant company. Please refer to the actual policies for terms, conditions, and exclusions of coverage. Coverage may not be available in all jurisdictions. ADDITIONAL INFORMATION Review Accounts and Credit Reports: You can regularly review statements from your accounts and periodically obtain your credit report from one or more of the national credit reporting companies. You may obtain a free copy of your credit report online at www.annualcreditreport.com, by calling toll-free 1-877- 322-8228, or by mailing an Annual Credit Report Request Form (available at www.annualcreditreport.com) to: Annual Credit Report Request Service, P.O. Box 105281, Atlanta, GA, 30348-5281. You may also purchase a copy of your credit report by contacting one or more of the three national credit reporting agencies listed below. 0000001 ENGAGE# ABCDEFGHI  If you have questions about the product, need assistance with Identity Restoration that arose as a result of this incident, or would like an alternative to enrolling in Experian IdentityWorks online, please contactExperian’s customer care team at --- by June , . Be prepared to provide engagementnumber ENGAGE# as proof of eligibility for the Identity Restoration services by Experian.

You should remain vigilant with respect to reviewing your account statements and credit reports, and you should promptly report any suspicious activity or suspected identity theft to the proper law enforcement authorities, including local law enforcement, your state’s attorney general, and/or the Federal Trade Commission (“FTC”). You may contact the FTC or your state’s regulatory authority to obtain additional information about avoiding and protecting against identity theft. The FTC can be reached at: Federal Trade Commission, Consumer Response Center 600 Pennsylvania Avenue, NW, Washington, DC 20580, 1-877- IDTHEFT (438-4338), www.ftc.gov/idtheft. For Washington, D.C. Residents: You may also obtain information about preventing and avoiding identity theft from the Washington D.C. Attorney General’s Office: Office of the Attorney General, 400 6th Street, NW, Washington, DC 20001, (202) 727-3400, https://oag.dc.gov/consumer-protection. For Maryland Residents: You may also obtain information about preventing and avoiding identity theft from the Maryland Office of the Attorney General: Maryland Office of the Attorney General, Consumer Protection Division, 200 St. Paul Place, Baltimore, MD 21202, 1-888-743-0023, www.oag.state.md.us. For New York Residents: You may also obtain information about preventing and avoiding identity theft from the New York Attorney General’s Office: Office of the Attorney General, The Capitol, Albany, NY 12224-0341, 1-800-771-7755, https://ag.ny.gov/internet/privacy-and-identity-theft. For North Carolina Residents: You may also obtain information about preventing and avoiding identity theft from North Carolina Attorney General’s Office: North Carolina Attorney General’s Office, Consumer Protection Division, 9001 Mail Service Center, Raleigh, NC 27699-9001, 1-877-5-NO-SCAM, www.ncdoj.gov. For Oregon Residents: You may also report suspected identity theft to local law enforcement, including the Oregon Office of the Attorney General: Oregon Office of the Attorney General, Consumer Protection, 1162 Court St. NE, Salem, OR 97301, 1-877-877-9392, https://www.doj.state.or.us/consumer- protection/id-theft-data-breaches/data-breaches/. For Rhode Island Residents: By law, you have a right to obtain a police report filed relating to these incidents (if any), and if you are the victim of identity theft, you also have the right to file a police report and obtain a copy of it. You may contact the Rhode Island Attorney General at: Rhode Island Office of the Attorney General, 150 South Main Street, Providence, RI 02903, 1-401-274-4400, www.riag.ri.gov. Security Freezes and Fraud Alerts: You have a right to place a security freeze on your credit report at no cost, which will prohibit a consumer reporting agency from releasing information in your credit report without your express authorization. The security freeze is designed to prevent credit, loans, and services from being approved in your name without your consent. However, you should be aware that using a security freeze to take control over who gets access to the personal and financial information in your credit report may delay, interfere with, or prohibit the timely approval of any subsequent request or application you make regarding a new loan, credit, mortgage, or any other account involving the extension of credit. You may request that a freeze be placed on your credit report by calling the numbers of the credit reporting agencies specified below, sending a request to the credit reporting agencies’ addresses specified below by certified mail, overnight mail or regular stamped mail, or by visiting the website addresses of the credit reporting agencies below. ENGAGE#

A security freeze does not apply to a person or entity, or its affiliates, or collection agencies acting on behalf of the person or entity, with which you have an existing account that requests information in your credit report for the purposes of reviewing or collecting the account. Reviewing the account includes activities related to account maintenance, monitoring, credit line increases, and account upgrades and enhancements. Please contact the three major credit reporting companies as specified below to find out more information about placing a security freeze on your credit report. As an alternative to a security freeze, you have the right to place an initial or extended fraud alert on your credit file at no cost. An initial fraud alert is a 1-year alert that is placed on a consumer’s credit file. Upon seeing a fraud alert display on a consumer’s credit file, a business is required to take steps to verify the consumer’s identity before extending new credit. If you are a victim of identity theft, you are entitled to an extended fraud alert, which is a fraud alert lasting 7 years. You can place a fraud alert on your credit report by contacting any of the three national credit reporting agencies at the addresses or toll-free numbers listed below. You can obtain more information about fraud alerts and credit freezes by contacting the FTC or one of the following national credit reporting agencies: Equifax (www.equifax.com) General Contact: P.O. Box 740241, Atlanta, GA 30374 800-685-1111 Fraud Alerts and Security Freezes: P.O. Box 740256, Atlanta, GA 30374 Experian (www.experian.com) General Contact: P.O. Box 2104, Allen, TX 75013 888-397-3742 Fraud Alerts and Security Freezes: P.O. Box 9556, Allen, TX 75013 TransUnion (www.transunion.com) General Contact, Fraud Alerts and Security Freezes: P.O. Box 2000, Chester, PA 19022 800-916-8800 0000001 ENGAGE#