Key Highlights

  • All five energy names are trading lower on Wednesday, October 28, 2026, from Canadian Solar down 2.59% to Centrus Energy down 0.45%.
  • Canadian Solar tops the ranking with about 13.6 days to cover on 19,452,394 shares sold short at the October 15 settlement date.
  • Sunrun has the largest short position by share count, 71,657,132 shares, equal to 8.64 days to cover.
  • Short positions equal 28.6% to 31.2% of shares outstanding at Canadian Solar, Centrus Energy and NANO Nuclear Energy (calculated).
  • FuelCell Energy has the shortest cover period at about 4.6 days, with 32.37% of float sold short at the September 30 settlement date.

Which Energy Stocks Are the Most Shorted on October 28?

Five energy names with heavy short positions are all trading lower on Wednesday, October 28, 2026. Centrus Energy (NYSEAMERICAN:LEU) is trading 0.45% lower at $108.93 after an 11.15% rise on Tuesday, and Sunrun (NASDAQ:RUN) is trading 2.06% lower at $7.38 ahead of third-quarter results on November 4. Canadian Solar (NASDAQ:CSIQ) is trading 2.59% lower at $9.42 with storage shipments up 82% from the first quarter, NANO Nuclear Energy (NASDAQ:NNE) is trading 2.27% lower at $12.06, and FuelCell Energy (NASDAQ:FCEL) is trading 1.72% lower at $11.97.

The ranking uses days to cover, the only short-interest measure available for all five. The bases for percentages differ: FuelCell Energy and Sunrun are measured against float, while Canadian Solar, Centrus Energy and NANO Nuclear Energy are measured against shares outstanding, so the percentages are not ranked together. Dates also differ, with FuelCell Energy and NANO Nuclear Energy at the September 30, 2026 settlement date and the other three at October 15. No company release dated October 28 is cited for any of the five.

1. Canadian Solar: Why Is a Heavily Shorted Stock Edging 2.59% Lower?

Canadian Solar makes solar modules, sells battery storage through its e-STORAGE unit and develops projects through Recurrent Energy. Shares are trading 2.59% lower at $9.42, an implied prior close of about $9.67 (calculated), and no release dated October 28 explains the dip. Short interest at the October 15 settlement date was 19,452,394 shares, down 399,835 (about 2.0%) from 19,852,229 on September 30, equal to about 28.6% of shares outstanding (calculated) and roughly 13.6 days to cover on average daily volume of 1,432,638 shares.

Second-quarter revenue reported August 27 was $1,207.7 million, down 29% from a year earlier, with a 13.9% gross margin and a net loss of $76.9 million. Storage shipments of 3.7 GWh were up 82% from the first quarter, and third-quarter revenue guidance is $1.3 billion to $1.5 billion.

2. Sunrun: Why Is the Stock Slipping Before Its November 4 Earnings Report?

Sunrun provides residential solar and battery storage, mostly through long-term customer agreements. Shares are trading 2.06% lower at $7.38 after closing at $7.27 on Monday, October 26, following a 4.09% decline that day, and no announcement accompanied today's move. Short interest at the October 15 settlement date was 71,657,132 shares, up 948,584 from 70,708,548 on September 30, with 8.64 days to cover on average daily volume of roughly 8.29 million shares; the September 30 reading equaled about 32% of float.

Second-quarter revenue rose 53% to $870.0 million, but 2026 guidance was lowered: Aggregate Subscriber Value is now expected at $4.6 billion to $4.9 billion from $4.8 billion to $5.2 billion, and cash generation at $200 million to $375 million from $250 million to $450 million.

3. NANO Nuclear Energy: Why Is a Reactor Developer Trading Lower With 31% Sold Short?

NANO Nuclear Energy is developing small modular reactors, including the KRONOS MMR, the ZEUS portable battery reactor and the LOKI MMR for space use. Shares are trading 2.27% lower at $12.06 after a 2.47% decline to $11.86 on Monday, October 26, and no dated company release accompanied the move. Short interest at the September 30 settlement date was 16,750,169 shares, up 1,291,946 from the prior reading, equal to about 31.2% of shares outstanding (calculated, as float is not reported) and 7.95 days to cover.

The company reported about $580 million of cash, equivalents and short-term investments at June 30, and a trailing twelve-month net loss of $33.85 million. The Nuclear Regulatory Commission docketed the KRONOS construction permit application in May 2026, with construction expected in the second half of 2027, and a three-year engineering agreement with IMPSA was signed October 21.

4. Centrus Energy: Why Is the Stock Little Changed After an 11.15% Rise?

Centrus supplies enriched uranium fuel and services for nuclear reactors and is expanding enrichment capacity, including HALEU. Shares are trading 0.45% lower at $108.93, a pause after an 11.15% gain on Tuesday, October 27, to $109.42 from a close near $98.44, and no company release dated October 27 or October 28 explains either move. Short interest at the October 15 settlement date was 5,933,422 shares, about 29.7% of the 19.95 million shares outstanding (calculated, not a float measure), with 6.79 days to cover versus 8.08 on September 30.

On October 19, 2026 the company announced the purchase of Westerman Holdings for about $116 million, paid with $95 million in cash and $21 million in shares. Second-quarter revenue was $176.1 million, and 2026 revenue guidance of $450 million to $500 million was maintained. A $900 million Department of Energy HALEU task order and an offtake agreement with Oklo (NYSE:OKLO) support the outlook, while the proposed fiscal 2027 federal budget includes no further HALEU operation funding, putting about $0.8 billion of backlog in question.

5. FuelCell Energy: What Is Behind the Dip in a Heavily Shorted Stock?

FuelCell Energy builds stationary fuel cell power platforms, with a recent pivot toward data center power. Shares are trading 1.72% lower at $11.97, an implied prior close of about $12.18 (calculated), after a 3.15% rise to $11.46 on Monday, October 26, and no release dated today explains the dip. Short interest at the September 30 settlement date was 24,465,442 shares, down 434,998 from September 15, equal to 32.37% of float with about 4.6 days to cover.

Fiscal third-quarter revenue reported September 2 was $33.0 million versus $46.7 million a year earlier,. The company holds a capital equipment purchase agreement with Fit Energy for up to 380 megawatts, with Phase 0 at 30 megawatts. Cash, equivalents and restricted cash were $737.3 million, and at $11.97 the shares sit about 43% below the $21.00 price of the July 9 offering (calculated).

Most Shorted Energy Stocks Compared: Cover Periods, Short Sizes and Moves

Canadian Solar's roughly 13.6 days to cover is about 9.0 days longer than FuelCell Energy's roughly 4.6 (calculated). Sunrun's 71,657,132 shares sold short are about 12.1 times Centrus Energy's 5,933,422 (calculated), yet its cover period is only 1.85 days longer, 8.64 versus 6.79 (calculated). On the shares-outstanding basis, NANO Nuclear Energy's 31.2% is 2.6 percentage points above Canadian Solar's 28.6%, with Centrus Energy's 29.7% between them (calculated).

On the day, Canadian Solar's 2.59% decline is 2.14 percentage points larger than Centrus Energy's 0.45%, while Sunrun and FuelCell Energy differ by only 0.34 points (calculated). Centrus Energy's $108.93 share price is $101.55 above Sunrun's $7.38 (calculated). Mixed dates and bases mean these comparisons describe positioning, not direction.

What to Watch Next: Sunrun's November 4 Report, Centrus Energy's November 5 Call and the October 30 Settlement

Sunrun reports third-quarter results on Wednesday, November 4, 2026, with subscriber additions and cash generation measured against its lowered guidance, and Centrus Energy holds its shareholder call on Thursday, November 5, 2026. Short-interest figures for the October 30 settlement date are expected on November 10 for Canadian Solar, Centrus Energy and Sunrun. FuelCell Energy faces the start of Phase 0 deliveries and fiscal fourth-quarter results for the period ending October 31, while Canadian Solar's third-quarter report and NANO Nuclear Energy's fiscal year-end results are undated.