The rapid expansion of artificial intelligence has led hyperscalers like Amazon, Microsoft, and Google to take on unprecedented levels of debt, shattering what analysts are calling the "unspoken contract" they once had with investors. For years, these tech giants maintained conservative financial strategies—prioritizing strong balance sheets, robust free cash flow, and minimal leverage. But the AI boom has upended that model. As companies race to build and scale massive data centers powered by cutting-edge AI chips, particularly from Nvidia, they are now borrowing heavily to fund infrastructure. This surge in capital expenditure, driven by AI ambitions, has led to a significant increase in debt levels across the sector. Skeptics are raising alarms. Shaan Raithatha, senior economist at Vanguard, noted that while hyperscalers still start from a position of strength—boasting powerful financial foundations and dominant market positions—there are growing concerns about hidden risks. "Are there hidden risks building in the system, whether it's special purpose vehicles, the greater leasing of assets, greater off-balance sheet activity? The hidden risks are building, we don't know if that's ever going to come up," Raithatha told CNBC's "Squawk Box Europe." He pointed to a key question investors must now consider: What happens if a breakthrough in AI hardware—perhaps from a Chinese competitor—renders today’s Nvidia-powered data centers obsolete within three to five years? "What if, in three years, these Nvidia chips get outstripped by a Chinese competitor, and I'm lending for five or eight years, and in year three, my data center is obsolete?" he asked. These concerns underscore a fundamental shift in investor expectations. Traditionally, the market rewarded stability and efficiency. Now, the focus is on aggressive growth and long-term AI dominance—often at the cost of financial prudence. As a result, future stock market returns may be discounted with greater caution, as the true cost and longevity of these AI investments remain uncertain. While the hyperscalers’ current cash flows and market power provide a buffer, the scale of their debt binge has introduced new vulnerabilities. Investors are being forced to weigh the promise of AI-driven growth against the potential for stranded assets and financial overextension. The unspoken contract—of fiscal discipline in exchange for trust—has been quietly broken.