Alphabet, parent company of Google, has become the world's second most valuable company, surpassing Apple with a market capitalization of $3.88 trillion. This surge is attributed to strong performance in its generative AI platform, Gemini, and its leadership in the robotaxi market via Waymo. Nvidia remains the most valuable company globally with a market cap of $4.59 trillion. Alphabet's stock has seen significant gains over the past year, outperforming Apple's performance.