A significant portion of the increase involves securities subject to the Securities and Exchange Commission’s Rule 144a, which allows institutional investors to purchase securities without an initial public offering. In 2024, private placement bonds rose 6.3% to nearly $1.8 trillion, making up over 45% of the industry’s bond holdings. Non-144a private placements, which are less liquid, reached more than $950 billion, accounting for 24% of the sector’s bond portfolio and 17% of invested assets.