EXHIBIT 99.1

 

JOINT FILING AGREEMENT

 

The undersigned hereby agree that the statement on Schedule 13G with respect to the Shares of MOUNTAIN LAKE ACQUISITION CORP. II dated as of March 31, 2026 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: May 14, 2026 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, Administrative Manager of Supernova Management LLC
   
Date: May 14, 2026 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, Administrative Manager of Supernova Management LLC
   
Date: May 14, 2026 supernova management llc
   
  By: /s/ Hayley Stein
  Name: Hayley Stein
  Title: Attorney-in-fact for David J. Snyderman, Administrative Manager
   
Date: May 14, 2026 DAVID J. SNYDERMAN
   
  By: /s/ Hayley Stein
  Name: Hayley Stein
  Title: Attorney-in-fact for David J. Snyderman