Accounting year-end dispersion and seasonality in the Japanese corporate bond market

Using monthly yield data on straight bonds, this article investigates seasonality in the Japanese corporate bond market. A statistical examination of spreads between the yield of each bond and a bond market index reveals that the yield spread consistently decreases from April to August, whereas it increases from September to December. Because accounting year-ends for most investors in Japan are concentrated in either March or December, this seasonality supports the hypotheses of tax-loss selling and window dressing. Moreover, the seasonality becomes more pronounced as the debt rating declines, consistent with the findings in previous studies investigating the US bond market.