[zeroname]

Okay, it seems like you don't understand the very basics.

A checking account holds 100% cash (dollars), not securities. That cash is insured by SIPC up to $250,000, just like the cash in your bank account is only insured up to $250,000.

Securities is things like stocks. Stocks are subject to significant gains, but also significant losses. That's the investment risk you have to take. There's no way around it. There can't be a government insurance against it. You can buy "insurance" against losses by purchasing options to sell at a specific price, or you can reduce risk by diversifying your portfolio.

I don't know the details of how securities are valued for recovery in the context of SIPC, but the point is that you will receive (parts of) your securities, not cash. Therefore, if for example you hold Microsoft stock at the time of bankruptcy of Robinhood, you are not entitled to be reimbursed any losses that may have occured as a result of Microsoft's stock price dropping in the meantime. Conversely, you do not owe any gains that the stock price may have made.