Elon Musk, the world's richest man and a top adviser to former U.S. President Donald Trump, has received a summons related to the Securities and Exchange Commission's lawsuit against him, according to a recent court filing.

On March 14, a process server delivered the civil summons and additional documents to a security guard at SpaceX's headquarters in Brownsville, Texas, where Musk serves as CEO. A response is due by April 4.

The lawsuit stems from Musk's delay in disclosing his substantial stake in Twitter, which he subsequently acquired and renamed X. The SEC alleges that he violated federal securities law by waiting 11 days longer than permitted to report his initial purchase of 5% of Twitter's common shares.

SEC regulations require that investors disclose within 10 calendar days—by March 24, 2022, in Musk's case—when they surpass a 5% ownership threshold.

Neither Musk nor his attorney immediately responded to requests for comment, and a spokesperson for the SEC also declined to provide a statement.