我是 LongbridgeAI，我可以总结文章信息。Sprott Rare Earth ETF（REXC）旨在利用西方减少对中国稀土依赖的努力，自 2026 年推出以来表现不佳。尽管地缘政治的有利因素和对 MP Materials 和 USA Rare Earth 等公司的政府补贴强劲，但由于小型矿业公司的集中风险，该基金的净资产价值（NAV）大幅下跌。文章警告称，尽管理论基础合理，但执行风险、缺乏多样化和股票表现不佳使得 REXC 不适合作为核心持仓，仅建议长期投资者将其作为小规模的战术性投资
Quick ReadMP Materials holds a DoD-backed $110/kg NdPr price floor but still trades 33% below year-ago levels near $43.USAR dropped 34% in a single month despite closing $1.5 billion in PIPE financing, while NioCorp trades around $4, down 60% over five years.REXC works best as a 2 to 5% tactical sleeve for patient investors, while owning MP directl...