PSUS: CIO Buys $9.6M as Borrow Stays Loose and Shorts Tick Higher

Pershing Square USA enters the final stretch of October with an unusual juxtaposition: its Chief Investment Officer spent nearly $9.6 million buying shares in early October, yet short interest has risen 16% over the past week, reaching its highest level in the 30-day window.

The insider story is the most concrete signal in the data. Ryan Israel, CIO, made three open-market purchases between October 2 and October 6, none under a 10b5-1 plan, totalling 256,613 shares at prices ranging from $37.21 to $37.87. That puts his net buy at roughly $9.6 million across the cluster, a conviction-weighted move rather than a routine transaction. His disclosed holding now stands at 756,613 shares. These were discretionary purchases, not pre-arranged plan sales, which makes them a more direct read on management's view of value.

Short interest is rising, but the scale remains small. Shares short climbed from around 240,000 to 295,644 between mid-October and last week, a 16% weekly gain. In absolute terms, that is still a modest number against a $3.8 billion market cap, and the borrow market is nowhere near stressed. Availability is exceptionally loose at roughly 1,260%, meaning around 3.2 million shares remain available to lend for every position currently borrowed. Borrowing costs have also eased sharply, falling to 0.65% from close to 1% a month ago. The ORTEX short score has drifted lower to 29.8 this week from 31.6 ten days ago, consistent with a positioning setup that looks more like quiet nibbling than any coordinated short thesis. The lack of squeeze pressure is notable given the insider buying cluster.

Options data offer little additional colour. The put/call ratio is balanced at 1.0, with only five sessions of history available, and the 52-week range spans from 0.0 to 1.33, so the current reading sits mid-range. There is no meaningful z-score context here given the thin history, and options liquidity in PSUS remains limited.

On the ownership side, the structure of the register is worth understanding. Pershing Square PSUS Holdings filed a Schedule 13D in May 2026, a registration that carries activist intent under SEC disclosure rules. That filer holds 100% of a separate share class, a structural feature of the vehicle rather than a conventional activist stake. The Teacher Retirement System of Texas remains the largest conventional institutional holder at around 10.1% of shares, though it trimmed its position in August, selling roughly 75,000 shares across several transactions at prices between $38.10 and $40.06, above where the stock trades now. William Ackman himself appears in the register at just under 5%. As a reminder, Schedule 13D and 13G positions are disclosed around the 5% threshold and may not reflect current holdings if a party has since moved below that level.

The stock closed at $37.86 on October 27, up 2.2% on the week and roughly flat over the past month. The price-to-book ratio sits near 0.70, consistent with the persistent NAV discount that has characterised PSUS since its listing. The PE sits at 6.4x, down from around 7.0x thirty days ago, reflecting the modest compression in reported earnings yield as the price has drifted. Wikipedia attention for the name has picked up, with a z-score of 2.24 against its own 90-day history, suggesting a small uptick in retail interest this week.

The gap to watch is whether the CIO's October buying cluster marks a floor or simply an opportunity cost against a continuing NAV discount. The pace at which short interest either reverses or accelerates from its current 295,644-share level will be the most direct indicator of whether other market participants share Israel's conviction.