The Invesco Semiconductors ETF PSI enters October with its most aggressive short-side build in months, even as the fund itself has quietly posted a 15% gain over the past month.
The dominant story this week is how fast the lending market has tightened. Short interest has more than doubled over the past five trading days, rising 113% to roughly 497,000 shares, or about 4% of free float. That pace of accumulation is striking for a broad-sector ETF, where shorts typically move slowly. Availability has collapsed in tandem: a week ago shares-available-to-borrow comfortably exceeded existing short interest several times over, with availability running above 160%. By Tuesday it had fallen to just 18.7%, the lowest reading of the past year, meaning for every share currently lent out, fewer than one-in-five additional shares remain available. Cost to borrow has moved with it, climbing 48% on the week to 2.33%, though that level remains modest in absolute terms and suggests the squeeze pressure is real but not yet painful. The ORTEX short score has drifted up in step, reaching 51.2 on September 29 from 42 two weeks earlier, consistent with a market that is recognising this build in real time.
Options positioning tells a calmer story and provides a useful counterpoint. The put/call ratio at 0.46 is only marginally above its 20-day average of 0.42, barely 0.7 standard deviations above the mean. For context, the 52-week high on the PCR is 0.90, so options traders are nowhere near peak defensiveness. Call volume continues to dominate, which lines up with the 1.7% gain on the week and the broader chip-sector tailwind that recent commentary has attributed to AI infrastructure demand and improving foundry utilisation. The two signals point in opposite directions: borrow demand is rising sharply, while options positioning remains constructive.
Institutional ownership data, current through June 30, shows a fragmented holder base with no single dominant owner above 3.3% of shares. LPL Financial, Meitav and HighTower are the three largest holders. Of note, Meitav added nearly 400,000 shares in the most recent reported quarter, the largest addition in the top-15 list, while Cetera trimmed 90,000. Two Sigma entered the register fresh with 111,300 shares. These are June figures and the sharp moves in borrow and short interest since mid-September will not yet be reflected in any institutional filing.
On the earnings history, the two most recent annual component rebalancing announcements produced an average one-day move of roughly 6% in absolute terms, alternating direction: a 6.1% drop in July 2026 and a 6.2% rally in January 2026. The five-day moves were similarly mixed. There is no scheduled earnings event for the fund itself, so the near-term catalyst is more likely to be a macro or sector-level development, whether that is a chip-sector guidance update, a tariff headline, or a shift in AI-spending expectations.
The key thing to monitor in the days ahead is whether borrow availability tightens further from its current record low or whether the short-interest build begins to reverse, because at 18.7% availability, the lending pool for new bearish positions is effectively running on fumes.
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