This 8-K reports Amendment No. 1 to the original Agreement and Plan of Merger between Vector Acquisition Corp (SPAC), Rocket Lab USA, Inc., and Merger Sub, dated May 7, 2021. The amendment details that upon Vector's domestication to Delaware, its Class A and B ordinary shares convert one-for-one to equivalent classes of Vector Delaware common stock. A temporary dual-class voting structure is introduced—Class A with 1 vote per share, Class B with 10 votes—to reduce administrative burden for the First Merger (Merger Sub into Vector Delaware). Following the Second Merger (Rocket Lab into Vector Delaware), the certificate amends to single-class common stock with equal voting rights. All other merger terms unchanged. Additionally, under Item 7.01, the parties confidentially submitted S-4 registration statement, to become proxy/prospectus upon effectiveness. This advances the SPAC Business Combination for Rocket Lab's public listing.

This is a minor procedural amendment facilitating the SPAC merger mechanics without altering economics or timelines, signaling progress toward Rocket Lab's public debut via Vector. No quantifiable financial impact. Strategic significance lies in streamlining path to Nasdaq listing; investors should monitor S-4 public filing, effectiveness, and shareholder approval for completion risks.