I heard somewhere that when you buy stocks through most online brokerages,  your not really considered the owner of those shares, but only have access to the shares the  through a trust of some sort.  In the event of a market halt or emergency the brokerage could just recall your shares or something to that effect.

Anyone?

I think what you're looking for is called holding in street name....

Wealthfront.com has this in it's faq


Everything is held in street name: Wealthfront only invests in SIPC covered securities registered in street name at the Depository Trust Company (DTC). That means the securities purchased on your behalf by Wealthfront are held separately from other Wealthfront assets and other assets of our brokerage partner (Apex Clearing) and are fully insured as described above.

Read about the DTC, ie the Depositors Trust Corporation. Therein lies the answers you seek to the question you have posed.