The Securities and Exchange Commission notched a key win Tuesday as it defended changes to a decades old data sharing rule meant to open data broker markets.

The unanimous opinion from the D.C. Circuit batted away a challenge to the rule filed by Gibson Dunn Partner Thomas Hungar on behalf of The Nasdaq Stock Market and other exchanges and data brokers. Circuit Judge Judith Rogers wrote in the opinion that the agency acted within its authority, and that claims about the arbitrary nature of the rule change were without merit.