Plug Power Inc. (NASDAQ:PLUG) shares are trading lower on Monday. This decline reflects sector-wide profit-taking as investors are rotating out of hydrogen stocks after weeks of significant gains.The Nasdaq is down 0.81% while the S&P 500 has shed 0.35%.The drop serves as a breather for the clean energy sector. A major rally recently boosted the industry. First-quarter earnings and rising AI-driven data center power demand fueled that upward move.Fading Post-Earnings MomentumThe alternative energy company reported its first-quarter results earlier this week. Revenue reached $163.5 million. This represents a 22% year-over-year increase.Plug Power reported a quarterly loss of 8 cents per share. The performance beat the analyst consensus estimate of a 9-cent loss. However, the post-earnings momentum faded heading into the weekend.On Wednesday, Susquehanna analyst Biju Perincheril maintained a neutral rating on the stock. Perincheril raised the price forecast from $2.75 to $3.75.Plug Power Technical Levels To WatchEven after Monday's pullback, PLUG is still holding above its key trend gauges: it's trading 2.3% above the 20-day SMA and 43.4% above the 200-day SMA, which keeps the bigger-picture uptrend intact.The 20-day SMA remains above the 50-day SMA, and the longer-term golden cross (50-day above 200-day) that formed in September 2025 continues to support a bullish trend structure.