Last month the US Security and Exchange Commission (SEC) voted to accept as a part of the National Market System a Consolidated Audit Trail data base.  This included a provision that:

“Tightened the clock synchronization standards for SROs to within 100 microseconds of the time maintained by the National Institute of Standards and Technology to enable regulators to better sequence order events across multiple exchanges and required the SROs to assess industry standards for clock synchronization based on the type of market participant or system, rather than the industry as a whole…”

The move in the US follows a similar action in Europe implementing MIFD II standards.

SEC Press Release