Reg NMS worked perfectly well Thursday but the crisis exposed its Achilles heel.

FORBES: Some Agreement on Speed Bumps for Market Panics

Earlier this year the Securities and Exchange Commission approved a regulation known as Reg NMS, which emphasises the need for markets to be speedy.

ECONOMIST: Good times rarely last

The NYSE was charged with violating Reg NMS when, starting in 2008, it transmitted data through two of its proprietary feeds starting before sending data to the consolidated feeds.

FORBES: Historic SEC Order Slams NYSE For Data Violations

Reg NMS does not cover commodity exchanges, which allows the member-owned, floor-trading New York Mercantile Exchange to sustain its old ways although competition from the all-electronic IntercontinentalExchange could also force it to change.

ECONOMIST: Good times rarely last

But the request to hold off the change comes after several high-tension days at NYSE and growing concerns among traders that the initiation of Reg NMS today will jam up communications among exchanges.

FORBES: Magazine Article