Bond yields indicate the direction of a country's interest rates. Yield is directly proportional to the interest rate a bond offers and inversely proportional to its price. If there is a higher demand for bonds, an issuer does not have to offer higher yields or interest rates to attract investors. But that drives up the prices of bonds that were issued earlier with higher interest rates. These prices go up till their yields correct to the new bond's yield. If, on the other hand, a new bond offers a higher yield, the prices of the earlier bonds correct till their yields level up to the yield of the new bond.