CLS heads into its October 27 earnings date with the stock up 25% over the past month and short sellers tentatively rebuilding positions, creating a mild but notable divergence between price strength and a quietly rising bearish footprint.
The more interesting story this week is valuation, not positioning. The price-to-earnings multiple has expanded by 3.4 turns over the past 30 days to nearly 21x, and the price-to-book ratio has climbed by 1.6 turns to 7.8x. Those are meaningful re-ratings in a single month. The EV/EBITDA multiple, at 14x, has been more stable and actually ticked down fractionally over 30 days, suggesting the PE expansion is earnings-estimate driven rather than pure multiple inflation. Still, a stock already flagged in recent notes for a stretched valuation (PE near 38x on the ORTEX stock score pillar, which blends trailing and forward measures) is becoming harder to justify on price alone, even with quality and momentum scores that rank in the top tier of TSX-listed names.
Short positioning is rising but remains too small to read as conviction. Short interest climbed 11% on the week to just over 1% of the free float, with the move accelerating in the final two sessions of September. That takes the total to roughly 1.18 million shares short, a bounce off what had been a multi-week trough. Borrowing costs are low at 0.46%, even after tripling week-on-week from a soft Monday reading of 0.22%, and availability is extremely loose at over 3,000% of short interest. There is no squeeze pressure, no borrow scarcity and no sign of a crowded short. This looks more like a handful of new positions being added into a strong run-up than any organised bearish campaign.
The CEO has been selling. Robert Mionis filed a cluster of open-market sales on September 23, totalling roughly 23,400 shares across eight transactions at prices in the CAD 360 to 367 range, worth approximately CAD 8.5 million in aggregate. President Todd Cooper filed a single sale of 20,118 shares on the same date at CAD 360, worth around CAD 7.2 million. All trades were executed under pre-arranged 10b5-1 plans, which reduces their signalling value considerably. A planned sale is a routine monetisation, not a statement of concern. Net insider activity over the trailing 90 days runs to roughly CAD 54 million in disposals, almost entirely plan-driven. On its own, that is not alarming, but it does mean insiders have been consistent sellers into the stock's remarkable year-to-date run.
On the institutional side, FMR (Fidelity) remains the largest disclosed holder at around 6.85% of shares. The 13D/G register shows no activist presence. Whale Rock trimmed from 5.1% to 4.03% in a filing from August 2025 and has since dropped below the 5% disclosure threshold, so its current position is unknown. BlackRock disclosed a 5.5% passive stake in January 2026. All activist-related data here reflects as-last-disclosed positions and should be read accordingly.
Earnings history on this stock is unusually positive. The July 2026 Q2 result produced a one-day move of 14.4% and a five-day gain of 21.8%, the strongest short-term reaction in recent history. The prior quarter showed a more modest 0.2% day-one move. With the EPS momentum scores running at the 88th to 89th percentile over 30 and 90 days respectively, the market has consistently expected Celestica to beat, and it has generally delivered. The key question into October 27 is whether the stock, now trading well above the level at which the last beat was cheered, has already priced in another strong quarter.
The October 27 print is where all these threads converge: a stretched multiple, rising short interest from a low base, plan-driven insider selling, and a peer group (JBL, FN) that gained 3 to 5% on the week alongside CLS rather than diverging. Whether the AI infrastructure and data-centre server demand that has driven Celestica's outperformance shows up in guidance as durably as it has in the trailing results is the number worth watching.
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