Energy Vault Holdings enters the final week of September with a striking tension: the stock has rallied 25% in a month, yet short sellers have quietly added to their positions rather than retreating.
The short-side story dominates this week's setup. Short interest has climbed to 19.3% of the free float — a high absolute level — and the one-week increase of 6.6% is the sharpest move in the past 30-day window. What makes the positioning notable is that shorts built into price strength: NRGV closed Tuesday at $4.77, up 16% on the week. That divergence — a surging stock and rising short interest simultaneously — puts the borrow market under real stress. Availability has tightened sharply, dropping to just 9.8%, meaning fewer than one share remains for every ten already borrowed. A week ago, that figure was closer to 18%. The 52-week availability low sits at just 2.1%, touched in mid-August, so there is room to tighten further. Cost to borrow has also moved up, jumping 69% over the week to 1.25% annualised — still relatively cheap in absolute terms, but the direction of travel is clear. The ORTEX short score ranks at 76.1, placing NRGV in the 98th percentile of short-side pressure across the universe.
Options traders are moving in the opposite direction to short sellers. The put/call ratio has dropped to 0.138 — the lowest reading in nearly a month and 1.5 standard deviations below its 20-day average of 0.17. With the PCR sitting comfortably above 0.26 as recently as mid-August, the shift is pronounced. Call volume now dwarfs puts by a wide margin, suggesting the options market is far more interested in capturing further upside than hedging against a reversal. The contrast with a short book that is actively growing makes this one of the more charged setups in the clean-energy space right now.
The Street is broadly constructive, though the most recently active analyst data is now about a month old. Following the August 11 earnings print — which sent the stock up 17% in a single day — both Roth Capital and Cantor Fitzgerald raised targets to $7, while Citigroup moved to $6. Goldman Sachs remains a notable outlier, holding a Sell rating with a $2 target as of March. The mean target of $6.21 implies roughly 30% upside from current levels, a spread that keeps bulls engaged. The bull case rests on a 1.25 GW hyperscaler contract expected to generate $500–600M in revenue through 2027 and a successful pivot toward an asset-ownership model. Bears point to financing risk in that transition and the possibility that intensifying competition or battery cost inflation impedes execution.
Ownership adds another layer of interest. CEO Robert Piconi holds a Schedule 13D activist filing, the most recent disclosing a 13.4% stake — a signal of direct management alignment with shareholders. BlackRock disclosed a 6% position in July, and Craig Effron separately filed a passive 13G showing 6.35% in August. On the insider-transaction side, director Dylan Hixon made four open-market purchases in mid-August totalling roughly $426,000 — all discretionary, none under a 10b5-1 plan. A director sale of $427,000 by Stephanie Unwin on August 26 partially offsets that signal. Net 90-day insider activity is marginally negative on value, so the picture is mixed rather than clearly directional. As always, the 13D/G stakes are as last disclosed and holders dropping below 5% are not required to file again.
The next earnings date is November 10. After the August print delivered a 17% one-day gain and a further 9% over the following week, the market will be watching whether the hyperscaler contract pipeline translates into hard revenue milestones — and whether a short book running near 20% of float can hold its nerve if the stock continues higher into that print.
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