On September 26, 2022, NioCorp Developments Ltd. and GX Acquisition Corp. II announced a definitive business combination agreement, with NioCorp set to acquire GXII. The transaction, scheduled to close in the first quarter of 2023, values the combined entity at approximately C$ 419.1 million (US$313.5 million). This acquisition will lead to NioCorp's listing on the Nasdaq Stock Exchange, while maintaining its presence on the Toronto Stock Exchange.

The deal could potentially provide up to $285 million in net cash from GXII's trust account, depending on GXII shareholder redemptions. Additionally, NioCorp signed non-binding letters of intent with Yorkville Advisors Global for two financing packages, potentially offering an additional C$108 million  (US$81 million). This includes C$21 million (US$16 million) in convertible debentures and a $65 million equity purchase facility.

NioCorp's CEO Mark A. Smith highlighted the deal's role in accelerating financing for the Elk Creek Project, emphasizing the development of U.S. supply chains for critical minerals. GXII's Dean C. Kehler also noted the Elk Creek Project's significance in the transition to a greener economy.

Legal advisors for NioCorp included Jones Day, Blake, Cassels and Graydon LLP, and GenCap Mining Advisory Ltd., while GXII was advised by Skadden, Arps, Slate, Meagher & Flom LLP, Stikeman Elliott LLP, and DLA Piper LLP. Cantor Fitzgerald & Co. and BTIG, LLC also served as capital markets advisors to GXII.