Subtenant shall not assign, sublease, mortgage, pledge or hypothecate its subleasehold interest or any part thereof, whether by operation of law or otherwise, without the prior written approval of Sublandlord, which approval shall not be unreasonably withheld conditioned or delayed. Any purported assignment, sublease or other pledge or conveyance in violation of this provision shall be null, void and of no legal effect. The merger of Subtenant with any other entity or the transfer of any controlling or managing ownership or beneficial interest in Subtenant, or the assignment of a substantial portion of the assets of Subtenant, whether or not located at the Premises, shall not constitute an assignment hereunder.