Be Ready — Magnificent

Prepare

Enable instant transaction alerts via text or push notification for every debit — this is your earliest warning system.
Keep your bank's fraud hotline number saved in your phone contacts (it is also on the back of your debit card).
Maintain a secondary bank account at a different institution with a small balance — gives you access to cash if your primary account is frozen during investigation.
Know your FDIC coverage — deposits up to $250,000 per depositor per bank are federally insured.

Never use debit cards online — use a credit card instead. Debit card fraud has weaker legal protections and directly affects your bank balance.
Use unique strong passwords for online banking and enable 2FA (preferably an authenticator app, not SMS).
Be alert to phishing — your bank will never ask for your full password, PIN, or 2FA code via email, text, or phone call.
Avoid logging into bank accounts on public Wi-Fi without a VPN.

Call your bank's fraud line immediately — available 24/7 at most major banks. Request the account be frozen and all unauthorized transactions flagged.
Change your online banking password and PIN from a secure device and network.
Document everything — write down dates, amounts, and descriptions of all unauthorized transactions before they disappear from the interface.
File a fraud dispute for each unauthorized transaction — your bank will investigate and provisionally credit your account within 5 business days (10 for new accounts) under Regulation E.
File an FTC report at ReportFraud.ftc.gov — creates an official record.
Check your email and other accounts — a compromised bank account often follows a compromised email address. Secure email first.
Under Regulation E, you are protected: 0 liability if reported within 2 days, up to $50 if within 60 days, potentially unlimited liability after 60 days — report immediately.