Corporate bond market liquidity is showing strong signs of expansion across both the United States and Europe, driven by more frequent trading in a broader range of individual debt securities from blue-chip issuers.In the US investment-grade market, concentration in top-tier debt has softened noticeably. A company’s top three bonds represented approximately 35% of overall trading volume in that firm's securities as of this month—marking a five percentage point drop compared to January 2023, according to Barclays strategist Zornitsa Todorova.