It's a new week and a new set of rumors for Apple's first foldable phone. If Tuesday's reports are true, the device will be called the Ultra, have a bookish shape and launch in September.

The main report comes from Bloomberg's Mark Gurman, who said the foldable is on track for a September launch, despite Nikkei Asia reporting that the phone might not launch until 2027 due to issues that cropped up during the engineering test phase.

Citing unnamed sources, Gurman said Apple will introduce the foldable phone in September alongside the iPhone 18 Pro and Pro Max. Those phones would likely go on sale about a week after being unveiled.

An Apple representative didn't immediately respond to a request for comment. It's important to note that while rumors abound, Apple has confirmed none of them -- not even the existence of a foldable iPhone.

Still, the earlier Nikkei Asia report was jarring enough to send Apple's stock down 5.1% before it rebounded later, Gurman noted. The Nikkei Asia story said unexpected issues had arisen during engineering testing and that more time was needed to make "necessary adjustments." Under a worst-case scenario, the first shipment of the foldables would not occur until 2027, the report said.

More from CNET: Foldable Phones Have Solved Nearly Every Trade-Off, Well Before Apple Debuts One

Looks like a book

Meanwhile, consumer tech reviewer Sonny Dickson posted images on X showing dummy models indicating how big the iPhone Fold, iPhone 18 Pro and iPhone 18 Pro Max might be. In the image, the foldable has an almost square shape when fully opened.

Dummy images are useful for phone accessory manufacturers -- such as case-makers -- so they can get a head start on mass production before the devices are launched. When phones are released, consumers are quick to order cases and other accessories, so the sizes need to be known. It is unclear whether the dummy models shown are actual mockups from Apple.

People who commented on X didn't seem to love the dummy images, particularly because the models shown appear to lack MagSafe, Apple's magnetic system on the back of the phone that lets chargers and other accessories snap on.

Stefan Moser wrote, "If the Fold is missing MagSafe, this will be a big NO for me."

There were other criticisms, too. 

An X user going by DasnkiCS posted that the phone looks "too wide, can't palm that easily in normal phone use." 

And another X user, Brosnan Hoban, wrote, "Fold looks like a credit card from 2050."

What's in a name?

Tuesday's other big rumor concerned the foldable's name. 

A leaker, Digital Chat Station, posted on the Chinese social site Weibo that the foldable iPhone could be called the iPhone Ultra. The post also said Chinese competitors may use the Ultra name for their own foldables to compete directly with Apple on design, specs, and price.

The predominant rumored name has been the iPhone Fold, but others have included Flip, Duo and iFold.

In March, Gurman wrote in his Power On newsletter that Apple was considering a full line of Ultra products, possibly including a foldable phone, an M6 MacBook Pro with OLED, a foldable iPad and high-end Macs. Gurman also said Apple might introduce AirPods with "computer-vision cameras" to send visual data to Siri for its AI assistant feature.

We've seen a steady stream of tidbits about the foldable recently. There could be a large inner screen for multitasking, and people could open apps side by side. There might also be two rear cameras, a front-facing camera and a Touch ID side button.

Whatever Apple finally comes up with, it will be playing catch-up. Other major phone-makers already have foldable phones on the market, including the Samsung Galaxy Z Fold 7, the Google Pixel 10 Pro Fold, the OnePlus Open, the Huawei Mate XT, the Honor Magic V5 and the Motorola Razr Ultra.