Arm shares jump 25% as post-earnings rally extends to second week

Arm shares rose more than 24% on Monday , extending a post-earnings rally into the second week .

The chipmaker is now up over 90% since it reported quarterly financials on Feb. 8 .

The stock is up 142% since Arm's initial public offering in September and is now worth about $148 billion .

SoftBank still owns 90% of the outstanding stock, meaning its stake has increased more than $61 billion .