As you may already know, our clearing firm (Velox) offers SIPC insurance up to 250k in cash and 500k in securities. SIPC insurance is designed to cover securities that are "off the market" (e.g. limited partnerships, pink sheet securities, penny stocks, etc). All major securities (e.g. Apple, Amazon, Netflix, etc) are held at the Deposit Trust Company (aka DTC) not the clearing house, in our case Velox. The DTC is a central record keeping company of all securities held by all investors. This is done because certificates are no longer issued for large companies (iFlip only manages securities held at the DTC under algorithms). These securities are electronically recorded as yours even if the clearing company goes under. The 500K in securities that are being insured by the SIPC are securities NOT held at the DTC.
So what does this mean for you? This means you can safely hold more than 500k in securities in your brokerage account so long as the assets are being held at the DTC. Again, most stocks that iFlip offers are held at the DTC.