SEC mandates client disclosure for U.S. activist investors

The U.S. Securities and Exchange Commission issued new corporate‑finance interpretations requiring activist investors to name the identities of their clients in 13D filings and proxy statements. The guidance, released on July 10, clarifies that investors using special‑purpose “sidecar” vehicles must disclose clients who invest more than $500, treating them as participants in limited partnerships that seek board‑room votes.

The rule is intended to boost transparency for companies targeted by activist campaigns, a practice previously seen in the 2022 Masimo Corp bylaws dispute. Hedge funds and other activist firms have long guarded client identities, arguing disclosure could deter investment and copycat activism. The SEC did not comment on the timing or motivation for the change.