Hindenburg Research on Wednesday took aim at Equinix, the $80 billion data center provider, and accused the company’s management of selling shareholders an “AI pipe dream” while manipulating key metrics to boost the appearance of profitability.

Hindenburg said it had taken a short position against Equinix, meaning it was betting that shares of the real estate investment trust, or REIT, would fall.

Equinix shares plunged 7% in pre-market trading on the report. The company’s customers include the cloud divisions of Amazon, Google and Microsoft, according to Equinix’s website.

The short seller said that Equinix reported maintenance expenses — a major cost center for REITs — as spending on growth, making it appear that “that the company’s cost to maintain its revenue base is lower than it actually is.”

Former Equinix employees and executives said that the pressure to misclassify capex as growth rather than maintenance came “from top management.”

Hindenburg said that the “questionable” accounting allowed Equinix to boost its adjusted funds from operations, a metric the company also used to determine executive stock grants.

Hindenburg has taken short positions against other big names, including Nikola, Icahn Enterprises and Gautam Adani’s conglomerate.

Equinix did not immediately respond to a request for comment.

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