Atomic settlement is the crypto-native successor to Delivery-versus-Payment (DvP), the settlement discipline that has governed securities markets since the 1970s. Under DvP, the cash leg and the asset leg are linked so that one cannot settle without the other — but in traditional markets this linkage is legal and operational, not cryptographic. A central securities depository (CSD) coordinates both legs across a settlement window, typically T+1 or T+2.

The key distinction is conditional finality versus simultaneous finality:

DvP (traditional): Legs settle within the same window; a failed leg triggers unwinding rules and possible buy-in penalties.
Atomic (on-chain): Both legs execute in a single transaction; if either fails, the entire transaction reverts — no partial state ever exists.
Herstatt risk: The 1974 collapse of Bankhaus Herstatt left counterparties who had paid Deutsche Mark but not received USD — the canonical motivation for DvP and, later, atomicity.

Settlement Model	Timing	Counterparty Exposure
Free-of-payment (FoP)	T+2 to T+5	Full principal
DvP (CSD)	T+1 to T+2	Intraday, mitigated by rules
Atomic (hash-chain)	Same block	Zero (revert on failure)