Surge in Short Interest Hits iShares iBonds Dec 2031 Term Treasury ETF The iShares iBonds Dec 2031 Term Treasury ETF (IBTL) saw short interest soar by 180% in April, reaching 46,300 shares. Despite this, institutional investors, including Ameriprise and Confluence, have recently increased their holdings, signaling continued confidence in the fund amid heightened market scrutiny.12