Tesla Inc's shares fell 6% premarket on Thursday, after Chief Executive Elon Musk and team's four-hour presentation failed to impress investors waiting for an affordable electric vehicle and a plan with a concrete timeline.

Musk and more than a dozen executives laid out fresh plans to cut assembly costs by half, invest in a new plant in Mexico and discussed the company's innovation in managing its operations at its investor day on Wednesday.

However, the event, where Musk revealed the EV maker's 'Master Plan 3', was short on details about the timeline or any new Tesla products.

"The markets were primed for a big announcement, perhaps on something like a more affordable new model," said Russ Mould, investment director at AJ Bell.

"Tesla had been on a tear so far in 2023. Then Musk raises his head above the parapet in an investor day presentation and the shares are sputtering ... It may just have been a case of failing to live up to the hype."

The stock, which had lost about two-thirds of its value in 2022, has climbed more than 60% so far this year.

"The timeline and cost details were limited, and the event lacked a Tesla-like surprise," Wells Fargo analyst Colin Langan said.

Tesla's events have created a stir on the internet in the past, with Musk's dance moves at the opening of the company's Berlin plant in 2022 and an event in China in 2020 going viral on social media.

The company's plan to use 75% less silicon carbide vehicles without compromising the performance or the efficiency of the car also weighed on semiconductor maker and supplier STMicroelectronics', shares.

The reduction plan was "bad news for the whole silicon carbide production chain and in particular for STMicro," Brokerage Equita said. It estimates that Tesla accounted for 70% of 2022 semiconductor sales at STMicro.

(Reporting by Nivedita Balu in Bengaluru; Additional reporting by Carlo Giovanni Boffa in Gdansk; Editing by Sriraj Kalluvila)