Nvidia could be staring at yet another massive loss in market value in recent years. Shares of the world's most valuable chipmaker fell more than 6% in Frankfurt trading on Monday, putting around $270 billion of its market cap at risk. This comes as investors reacted to an internal investigation involving CEO Jensen Huang and allegations of a foreign intelligence operation relating to a relationship with an alleged Chinese spy.Nvidia has suffered two much larger single-day market-capitalisation losses in the last two years, including the record-breaking rout triggered by Chinese AI startup DeepSeek in January 2025.Citing LSEG Datastream, Reuters reported that the Frankfurt decline put approximately $270 billion of Nvidia's market value at risk, extending last week's losses and touching multi-month lows.Nvidia's biggest market-value losses in the pastNvidia earlier lost $279 billion in market capitalisation after its shares fell 9.5% on September 3, 2024 amid a broader Wall Street sell-off. This is as AI optimism dipped following weaker-than-expected economic data. Reuters had described it at the time as the biggest single-day market-value loss for a US company.The next major decline came on January 27, 2025, when DeepSeek triggered a global sell-off in tech stocks. Nvidia shares fell nearly 17%, wiping out $593 billion in market value in a single session, according to Reuters citing LSEG data. It then became the biggest one-day market-cap loss recorded by a company on Wall Street.The DeepSeek-related sell off was triggered by concerns that the Chinese startup's lower-cost AI models could challenge teh already established AI players and reduce the need for expensive chips and data centre infra.The latest pressure in today's trading follows reports that US intelligence officials believe Huang had been targeted by a foreign intelligence effort through his reported relationship with Alice Huang, a former executive at Singapore-based Megaspeed, and the chipmaker is facing scrutiny over suspected diversion of Nvidia chips to China. Beijing has, however, rejected the espionage allegations as baseless.Nvidia also announced an independent investigation on Sunday, and Huang has admitted to being unfaithful to his wife but has not publicly disclosed details of his relationship with Alice. Additionally, the company's board has expressed confidence in him and said it has no reason to believe that national security or trade secrets were compromised.Pepperstone's head of research Chris Weston told Reuters that the controversy was adding pressure to the stock, but did not expect Huang to be replaced.