A reversal in a crowded AI trade
Investors betting against five U.S.-listed cloud and data-center companies have accumulated about $6 billion in unrealized October gains as concern grows over the debt used to finance artificial-intelligence infrastructure. The estimate from analytics firm ORTEX covers CoreWeave, IREN, Nebius Group, Applied Digital and Core Scientific, according to Reuters.
The result is a paper gain, meaning it can change before positions are closed. It nevertheless shows how quickly sentiment has shifted in a market segment that attracted large amounts of capital on expectations for sustained demand for computing capacity. When shares fall, short sellers can profit by buying back stock for less than the price at which they borrowed and sold it; when prices rise, their losses can be substantial.
Heavy short interest and sharp moves
Short interest across the five companies ranged from roughly 20 percent to 26 percent of freely traded shares. CoreWeave’s short interest stood at 23.7 percent, up from 19.6 percent at the beginning of October. Its shares had fallen almost 30 percent during the month, producing about $1.7 billion in paper gains for short sellers.
Nebius short sellers held nearly $2.94 billion in October paper gains, although their positions remained down about $3.33 billion for the year. Bets against IREN and Applied Digital generated more than $1.2 billion in combined monthly gains, while Core Scientific added about $115 million. ORTEX estimated that around $17 billion of stock in the group was sold short.
Debt is at the center of the debate
Specialized cloud companies are racing to acquire chips, secure power and build data centers for AI customers. Those assets require large upfront spending, while revenue arrives over time and can depend on a limited number of contracts. Borrowing can accelerate construction, but it also increases fixed payments and refinancing exposure if demand, prices or completion schedules disappoint.
Supporters of the companies argue that computing demand remains strong and that new capacity can produce durable cash flow. Skeptics focus on leverage, customer concentration, equipment depreciation and the pace at which newer chips may reduce the value of existing systems. The current selloff reflects that disagreement rather than a settled conclusion about the industry’s future.
Borrowing conditions add another variable. ORTEX said the cost of borrowing shares for the five short positions remained relatively low, so traders were not yet paying an exceptional premium to maintain their bets. Corporate financing is different: interest expense, collateral terms and access to future capital can influence whether operators can complete facilities before customer contracts begin generating enough cash.
How to read the headline number
Short-selling data can reveal market pressure, but it does not prove that a business is overvalued or financially weak. A heavily shorted stock may continue falling, recover sharply or become volatile when traders rush to close positions. The $6 billion figure aggregates five different companies with distinct contracts, balance sheets and strategies.
For investors, the more durable questions are how much cash each operator must spend, when facilities begin producing revenue, the terms of its debt and the credit quality of its customers. October’s gains for short sellers are a clear measure of changed sentiment. Whether they become realized profits will depend on what happens next to share prices and on when those traders choose to exit.
Source: Reuters reporting based on ORTEX data. Reporting reviewed October 22, 2026.