Key PointsDuring his final press conference as Federal Reserve chair, Jerome Powell warned of a highly uncertain economic outlook tied to tariffs and elevated energy prices.The yield on the 30-year Treasury bond recently reached 5.18% due to expectations that the Fed will raise interest rates to combat inflation.The 30-year Treasury bond has not paid such a hefty yield since 2007, and the S&P 500 declined more than 20% the last time it happened.…