Charles Schwab is a member of the Securities Investor Protection Corporation (SIPC), the assets you have custodied are insured by SIPC up to $500,000 for each separate account including up to $1,000,000 in cash.
Such insurance DOES NOT protect your investment principal from market fluctuation or volatility; however it does provide an amount of protection in the event of your custodian going out of business.
Schwab maintains physical, electronic, and procedural safeguards that comply with federal standards to guard your nonpublic personal information. To learn more about their security measures and the measures you need to take, please click the Privacy link on the Schwab websites.