The Wall Street saying is that interest rates move inversely to bond prices. This is like when a stock price declines the dividend yield rises. For example, a stock that pays $4 per year would have a yield =4%%, if the stock’s price were $100 (4/100=4%). If the dividend remains the same and the stock price falls to $50, the yield would climb to 8% (4/50=8%). So it is with bonds which typically have a fixed interest rate/dividend. Falling bond prices = higher interest rates. TLT gapped down on Thursday.