Shares in controversial AI and defence technology stock Palantir keep hitting record highs, brushing off a New York Times report about fresh US government work and revived concerns over surveillance.

Palantir was cofounded by Peter Thiel, an early Trump backer, and several Trump administration figures have ties to the company. Investors don’t mind: quite the opposite, with the stock up almost sixfold in a year.

Now valued at $320 billion, Palantir is the 25th biggest stock in the S&P 500, just ahead of Coca-Cola, and just behind Bank of America.

In fact, it’s one of the most expensive large-cap stocks ever, says Trivariate Research’s Adam Parker. The former Morgan Stanley analyst notes its enterprise value is an eye-watering 73 times projected sales. Only six US companies have ever hit that level, most of them obscure biotechs or dotcom flame-outs.

Palantir’s implied growth rate – over 40 per cent annually for a decade – is “unprecedented” for a company of its size.

Palantir, Parker concludes, “might be fundamentally awesome”, but no company has ever grown fast enough to justify a price tag like this.