SA analyst upgrades/downgrades: NVDA, LMT, SHAK, SHOP

The article is a Seeking Alpha analyst roundup focused on upgrades and downgrades across several stocks, with Nvidia (NVDA) highlighted as the key name. Lockheed Martin is upgraded on expectations of stronger global defense spending and higher weapons production, while Shopify is upgraded as a post-pullback buying opportunity supported by solid revenue growth, margin expansion, and AI-related upside. Nvidia is downgraded despite strong recent earnings because its near-term upside appears limited, momentum has stalled, and investors may have already priced in much of the data-center growth story. Overall, the piece is mildly mixed for the chip sector, bullish on defense and e-commerce, and cautious on NVDA due to valuation and execution-risk concerns.