Magnetar Financial SC 13G Newbury Street II Acquisition / Magnetar Financial ownership change

EXHIBIT 99.1

JOINT FILING AGREEMENT

The undersigned hereby agree that the statement on Schedule 13G with respect to the Shares of NEWBURY STREET II ACQUISITION CORP. dated as of December 31, 2024 is, and any amendments thereto (including amendments on Schedule 13G) signed by each of the undersigned shall be, filed on behalf of each of us pursuant to and in accordance with the previsions of Rule13d-1(k) under the Securities Exchange Act of 1934, as amended.

Date: January 29, 2025	MAGNETAR FINANCIAL LLC
	By: Magnetar Capital Partners LP, its Sole Member
	By:	/s/ Hayley Stein
	Name:	Hayley Stein
	Title:	Attorney-in-fact for David J. Snyderman, Manager of Supernova Management LLC
Date: January 29, 2025	MAGNETAR CAPITAL PARTNERS LP
	By: Supernova Management LLC, its General Partner
	By:	/s/ Hayley Stein
	Name:	Hayley Stein
	Title:	Attorney-in-fact for David J. Snyderman, Manager of Supernova Management LLC
Date: January 29, 2025	SUPERNOVA MANAGEMENT LLC
	By:	/s/ Hayley Stein
	Name:	Hayley Stein
	Title:	Attorney-in-fact for David J. Snyderman, Manager
Date: January 29, 2025	DAVID J. SNYDERMAN
	By:	/s/ Hayley Stein
	Name:	Hayley Stein
	Title:	Attorney-in-fact for David J. Snyderman