I think DTC is just stocks (or bonds) held in "Street Name".
DTC used to be a large warehouse in Long Island City, Queens, NY.
Owned by NYSE.
On the other hand,
If you bought 100 shares XYZ and had the physical certificate mailed to your house,
that is NOT in "Street Name".
But of course you can still sell it, just deliver it to your broker.
They will send it to the Transfer Agent.
That's from years ago, at least.
And that's how Bernie Madoff scammed the regulators.
His accounts had nothing in Street Name, but the SEC never even checked.
A total BS Ponzi Scheme by Madoff, and the SEC lawyers couldn't figure it out.