Just a few trading days into the new year and Nvidia stock is already up sharply.As if its 171% gain in 2024 wasn't enough, shares of Nvidia (NVDA 2.36%) were already up about 9% by market close on Jan. 6. This was almost eight percentage points more than the S&P 500's year-to-date returns. Such staggering momentum probably has many investors wondering how long the stock can keep rising so rapidly. While there's no certain way to know how high the graphics processing unit (GPU) specialist's stock will go in ...