IWM enters the back half of September with a notable shift in the lending market — one that contrasts sharply with the previous week's story of surging borrow costs and tightening conditions.
The most striking development is how quickly the borrow environment has reversed. Last week's note flagged a cost-to-borrow that had more than doubled to 2.48%. That spike has since unwound almost entirely — borrowing costs have fallen 44% week-on-week, back to roughly 1.39%. That is still above the August baseline of sub-1%, but the direction has clearly turned. Availability has also swung dramatically. After spending most of early September in very tight territory — as low as 9.5% on Monday — availability has loosened back to 54.5%, leaving around 39.5 million shares available in the lending pool. That is still in the tight-to-normal band, but it is a meaningful improvement from conditions that were, briefly, near their tightest in a year.
Short interest itself has barely moved despite the borrow reversal, and that is the more important signal. The total short position eased about 5% in a single session on September 22 — from roughly 85.9 million to 81.4 million shares — but that single-day drop brings the week's net change to a near-flat +0.55%. More telling is the one-month picture: short interest has grown around 9.2%, adding approximately 7 million shares since mid-August. That trend was in place before borrow costs spiked, and it has persisted through the spike and the reversal. At 28.1% of free float, this remains a heavily shorted ETF by any standard. The FINRA fortnightly data puts days-to-cover at 4.8 — not extreme, but enough to make any rapid unwind complicated. The ORTEX short score holds at 71.5, essentially unchanged across the past two weeks, confirming that the positioning signal is stable and not deteriorating.
Options positioning adds a different layer. The put/call ratio has actually eased relative to its recent average. At 2.33, it is running about 1.5 standard deviations below its 20-day mean of 2.42 — the first time in weeks that options traders have looked less defensive than usual on the Russell 2000. The PCR has been trending lower since mid-August, when it was printing above 2.6. That is a slow drift toward less put-heavy positioning, even as short interest has been building. The contrast is worth naming: options traders are incrementally less bearish; short sellers are not.
The institutional picture offers one further piece of context. The top holders in the most recent 13F cycle are largely the major dealer desks — Bank of America with just under 10% of shares, Morgan Stanley at 6.4%, Goldman Sachs at 5.8% — and most were trimming in the June quarter. Wells Fargo added around 2.3 million shares; everyone else in the top three cut. That is the pattern of hedging and delta-hedging activity rather than conviction ownership, which is broadly expected for a major index ETF. BlackRock, the ETF's own sponsor, added a modest 394,000 shares through August.
The price itself has done little to resolve the tension. IWM closed at $287.21, up about 0.6% on the day and 0.7% on the week, but still down 4.3% on the month. Small-caps remain under pressure relative to where they began September, and the short book has grown into that weakness rather than covering it.
What to watch next: whether the availability improvement holds and borrowing costs stabilise around current levels, or whether the brief September spike turns out to be the first of several as short sellers look to rebuild and demand for borrows re-emerges against a still-shorted, still-weak small-cap tape.
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