Wall Street Fights Over Tab for Massive Stock-Trade Database (3)

A long-standing fight over who should pay for an expansive market-surveillance system intensified on Wednesday as the Securities and Exchange Commission stuck brokers with most of the bill.

The plan, approved by three of the five commissioners, faces stiff opposition from industry trade groups, heavyweight players like Citadel Securities and Virtu Financial Inc., and others that act as brokers or asset managers.

The system, known as the Consolidated Audit Trail, or CAT, is designed to track billions of daily equities and options trades a day. It’s intended to help the SEC catch manipulators and diagnose the causes of market ...