See the Vanguard's online fraud policy link at the link provided by Mike (MHalley) above:
https://personal.vanguard.com/us/help/S ... ontent.jsp
"Vanguard's online fraud policy
Our commitment regarding online security is simple. If assets are taken from your account in an unauthorized online transaction on Vanguard.com®—and you've followed the steps described in the Your responsibilities section below—we will reimburse the assets taken from your account in the unauthorized transaction.
By working together, we can help maximize the safety of your accounts and your personal information.
At a minimum, in order for this protection to apply, you must take the following steps:
Review your accounts regularly.
* Check your account frequently. Promptly and completely review all information we send you.
* Report any errors or discrepancies in your account and any suspected unauthorized transactions or account changes to Vanguard immediately.
Protect your Vanguard.com user name, password, and other account-related information.
* Make sure your user name, password, and answers to your security questions are unique and strong.
* Never share your user name, password, or other account-related information with anyone.
* Never store your user name, password, or answers to security questions in your browser.
* Clear any temporarily . . .
Protect your computer.
* Make certain that . . .
Do not reply to e-mail requests for personal or financial information.
* Do not . . .
Cooperate with us and stay informed.
* Cooperate . . .
As an added precaution, . . .
Details regarding this protection: This protection applies only to the following types of Vanguard® accounts: Vanguard nonretirement mutual fund accounts; Vanguard individual retirement accounts (IRAs); accounts maintained with Vanguard Brokerage Services®, a division of Vanguard Marketing Corporation; and participant accounts in retirement plans for which Vanguard provides recordkeeping and administrative services. Accordingly, this protection does not apply to annuities or to 529 college savings plan accounts.
This protection does not apply to unauthorized activity caused in whole or in part by your fraudulent, intentional, or negligent acts or omissions, including . . .
Vanguard will determine . . .
Vanguard may seek restitution . . . "