Morgan Stanley's analysis of Q2 13F filings reveals that Nvidia (ticker: NVDA) has become the most under-owned mega-cap technology stock relative to its weighting in the S&P 500 index. As of the end of Q2 2025, Nvidia's institutional ownership was 2.41% below its S&P 500 weight, marking the largest underweighting among mega-cap tech companies. This level of under-ownership is notable, with only Microsoft (MSFT) in Q2 2024 showing a more pronounced underweighting over the past 16 years. Nvidia's $4.33 billion stock portfolio is heavily concentrated in CoreWeave, which accounts for 91.36% of its holdings, followed by smaller stakes in Arm (4.11%), Applied Digital (1.79%), Nebius (1.52%), Recursion Pharmaceuticals (0.90%), and WeRide. Despite this institutional under-ownership, Nvidia shares declined by 2.9% following the report.