Apple shares hit record highs on Thursday after it said it would host an event on 12 September at its Cupertino campus where it is widely expected to unveil new iPhone models.

At one point its shares rose to more than $228 each amid speculation that Apple plans to release three new smartphones this year, including one with a larger display than previous models. Analysts also expect Apple to release an iPhone with a edge-to-edge display similar to the iPhone X but using less-costly LCD screen technology.

Apple’s event invitation made heavy use of the colour gold, fuelling speculation the company plans to launch a gold-coloured successor to the iPhone X, which was made available in silver and gray last year.

Documents filed at the US Federal Communications Commission and unsealed this year show Apple had sought approval for a gold version of its iPhone X.

A few hours after Apple’s announcement, 9to5Mac, a technology news website, posted photographs of two gold iPhone models stacked on top each other, with a larger-screened model on the bottom. Both models resemble the current iPhone X.

The site said the new flagship model will be called the iPhone XS and that Apple also planned to release a new version of the Apple Watch with a larger display by reducing the edges around it.

9to5Mac told Reuters the photographs were not mockups and represented Apple’s actual planned products but declined to say how it had obtained them. Apple did not respond to requests for comment about the authenticity of the photos.

Apple has for years released its new phone models in the second week of September, and often updates other product lines such as the Apple Watch at the event. The company has already given base-model iPads and some MacBook laptops an update this year.

Apple typically starts selling new iPhones a few weeks after launching them, in time for the holiday shopping season. The iPhone X, priced from $999, has helped Apple beat Wall Street sales expectations.

Investor Warren Buffett, speaking on Thursday to CNBC, said the iPhone was “enormously underpriced” even when it costs $1,000, given how indispensable it had become for so many people.