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SPY enters the back half of October with short positions near their recent peak and a borrow market that has tightened dramatically in just two weeks, even as the ETF itself has barely moved.
The short interest story has not changed in direction, only in degree. Borrowed shares climbed to 100.5 million as of October 13, equivalent to 9.79% of the free float. That is up 1.7% on the week and 10.2% from a month ago, consistent with the steady build documented in prior notes. The FINRA fortnightly settlement figure, struck at September 30, showed 98.5 million shares short with 2.0 days to cover, tracking closely with ORTEX estimates. What has shifted is the borrow market's texture. The ORTEX short score has risen to 50.1, its highest reading in the 10-day history captured here, moving out of the broadly neutral band it occupied through early October.
The most striking development this week is the collapse in borrow availability. Two weeks ago availability was running above 1,500%, meaning lenders had more than 15 shares available for every 10 already out on loan. That figure has now fallen to 607%, still comfortably loose in absolute terms but a 60% decline in a fortnight. The 52-week tightest reading was 34%, so there is no squeeze pressure yet, but the direction of travel has changed abruptly. Borrowing costs, at 0.36%, remain low and have actually eased 25% on the week after a mid-month spike. That divergence, availability tightening while cost-to-borrow falls, suggests lenders are pulling back inventory rather than pricing it higher.
Options positioning tells a different story from the shorts. The put/call ratio has eased to 1.93, right at its 20-day average and a full 0.4 points below the September peak of 2.33. The z-score of negative 0.06 confirms there is no directional lean in the options market at present. Traders who were paying heavily for downside protection through mid-September have let much of that hedging roll off, even as the short book has grown. The two signals are pointing in opposite directions: short sellers are adding, options buyers are not panicking.
The institutional picture explains some of the flow mechanics. As of the June quarter, the largest disclosed holders include market makers and trading firms whose SPY positions are working capital rather than directional conviction. Jane Street added 24 million shares in Q2 to hold 44.3 million. D. E. Shaw added 13.3 million shares to reach 14 million held. These are not long-term allocators making a directional call; they are firms whose book changes rapidly. Separately, JPMorgan added 1.8 million shares while Morgan Stanley and Goldman both trimmed, reducing by 8.1 million and 4.3 million respectively. The net picture across the top 15 holders is modest inflows, consistent with SPY's 1.8% one-month gain to $778.01.
The next pressure point is the interaction between the short build and the availability trend. Short interest is at its highest level in the period tracked, the short score is at a new high for the run, and availability is tightening at a pace not seen in recent weeks. None of those conditions individually signals stress, but the direction of each is the same, and that alignment is worth monitoring as the ETF approaches month-end.
See the live data behind this article on ORTEX.
Open SPY on ORTEX →ORTEX Market Intelligence content is generated by AI from a snapshot of ORTEX's proprietary data and reviewed by the ORTEX team. Content is informational only and does not constitute investment advice.
