For your investing account, your money will be held in a brokerage account provided by Alpaca - a FINRA-regulated brokerage firm.
The brokerage firm is a member of the Securities Investor Protection Corporation (SIPC), which protects the securities and cash in your account up to $500,000 of which up to $250,000 may be in cash. However, SIPC does not protect against market risk and general losses in the stock market.