SoftBank Group shares jumped 11.9% on Friday.
The two-day rally added more than $61 billion to the Japanese technology conglomerate's market capitalization.
Surging demand for AI infrastructure drove a significant rally in subsidiary Arm Holdings, fueling SoftBank's gains.
Broad investor enthusiasm for artificial intelligence increased following strong earnings from Nvidia.
Analysts view SoftBank as a public-market proxy for the global AI buildout.
Market sentiment also improved amid speculation regarding an initial public offering for OpenAI, where SoftBank is a major investor.