The article explores how the ease of buying and selling bonds affects their prices. By studying German government bonds from 1992 to 1994, the researchers found that bond prices not only change with interest rates but also with how easy it is to trade them. Bonds that are harder to trade tend to be priced lower than more liquid bonds. This means that bond liquidity should be considered when determining bond prices, alongside interest rates. The researchers' model was shown to be more accurate in predicting bond prices than traditional models.