Rocket Lab USA, Inc. shares plummeted 5.13% during intraday trading, as a combination of large-scale insider selling by its CEO and broad-based weakness across the Aerospace & Defense sector drove the stock lower.

The decline was primarily fueled by ongoing pressure from CEO Peter Beck's substantial share divestiture. Beck has cumulatively sold approximately 2.81 million shares through a pre-established 10b5-1 trading plan, and has filed to sell an additional 5 million shares valued at roughly $465 million. The magnitude of the insider sales has persistently dampened investor sentiment and confidence in the stock.

Sector-wide headwinds compounded the selling pressure, with notable declines in peers such as Boeing, FTAI Aviation, and GE Aerospace. The broad weakness in the industry added to the negative momentum for Rocket Lab, which has now fallen over 50% since late May and remains in a sustained downtrend.