This AI stock has nearly quadrupled in 2025.What companies come to mind first when you hear the words "artificial intelligence"? I suspect that Nvidia, ChatGPT creator OpenAI, or Google parent Alphabet would rank near the top of the list for many investors.On the other hand, I doubt that Nebius Group (NBIS -0.22%) would be among the most common responses. But maybe it should. This underrated AI stock could be the best growth story of the decade. "Exciting times"Nebius' primary focus is on its AI cloud platf ...