SHY, the iShares 1-3 Year Treasury Bond ETF, enters the final day of September with its lending market at its tightest point in at least a year, even as short interest falls and options positioning turns notably less defensive.
The sharpest move this week is in borrow availability. Availability has dropped to just 17.3%, the lowest reading in 52 weeks, meaning roughly one share remains available to borrow for every five already lent out. That marks a dramatic tightening from 81.6% as recently as last Thursday, a drop of nearly 78% in a single week. The speed of the move is notable: as recently as early September, availability sat above 100%, when there were more shares available to lend than already borrowed. Cost to borrow, at 1.14%, remains relatively modest in absolute terms, but has been volatile, ranging from 0.54% to 1.40% across the past two weeks. The tightening availability has not yet driven a meaningful borrow-cost spike, but the supply of shares to borrow is clearly being absorbed fast.
Short interest, by contrast, is moving in the opposite direction, and that divergence is the week's central tension. At 6.4% of the free float, the short position is genuinely meaningful for a Treasury ETF, but it has fallen 12.8% over the past week, unwinding a build that peaked above 7% of float in mid-September. The FINRA fortnightly figure, settled as of September 15, showed 18.6 million shares short with days-to-cover at 3.85. The ORTEX daily estimate now puts the figure slightly below that, at 18.4 million, suggesting shorts have continued to trim. The short score, at 62.1 out of 100, has also eased from a recent high of 66.2 on September 16, confirming the direction of travel.
Options positioning adds another layer. Demand for puts relative to calls has softened materially, with the put/call ratio at 1.79, nearly 1.6 standard deviations below its 20-day average of 3.0. The 52-week range runs from 0.06 to 4.58, and the ratio was running consistently above 3.5 through early September before falling sharply. That prior elevated PCR pointed to heavy protection-buying, presumably by investors hedging rate risk or equity-to-bond rotation plays. The move lower in the PCR suggests that defensive hedging through SHY options has unwound, a shift in tone worth watching given it coincides with the availability tightening.
Institutional ownership is broad and dominated by wealth management platforms. Morgan Stanley holds 7.8% of shares, CapFinancial 7.0%, and Strategic Advisers added heavily in the quarter to June, adding 7.4 million shares to reach 3.8% of the fund. JPMorgan trimmed by 3.5 million shares over the same period. The monthly dividend has run consistently near $0.24 to $0.25 per share through 2026, reflecting the short-duration yield the fund captures from 1-3 year Treasuries.
The divergence between tightening borrow supply and falling short interest is the key setup to watch. If shorts have genuinely covered and demand to borrow remains high for other reasons, availability could continue to compress without a squeeze dynamic. If fresh shorts are building under the surface, the low availability and manageable cost-to-borrow environment could reprice quickly.
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