Nvidia is making investors nervous.

After reports of Nvidia in talks for deals worth more than $750 billion — with OpenAI, among others — insurance on Nvidia’s debt got more expensive. “There’s a fear of financial alchemy driven by opaqueness, off-balance-sheet transactions and intercompany relationships, which could result in credit rating downgrades,” Sal Naro, chief investment officer of Coherence Credit Strategies, told Bloomberg. Nvidia is at the center of many transactions that tie the AI ecosystem together.