The rare-earth materials and magnets company's strategic importance to the U.S. was reinforced recently.Shares in rare-earth materials and magnets company MP Materials (MP +3.31%) rose by 12.3% in the week to Friday morning. The move comes as a BMO analyst upgraded his target on the stock from "hold" to "buy" and gave it a $75 price target.A buying opportunityThe upgrade comes after a recent sell-off off which the analyst believes is creating a useful entry point. Moreover, the company's long-term fundament ...