Elon Musk, the CEO of Tesla, revealed the electric carmaker has not signed a contract with Hertz, more than a week after the car rental giant announced a huge deal with Tesla.

Tesla's stock slumped 5% to $1,146 in premarket trading, after a sharp rise following the announcement on Oct. 25 of the company's largest-ever purchase - 100,000 electric cars for Hertz - which helped the company surpass $1 trillion in market capitalization.

"If any of this is based on Hertz, I'd like to emphasize that no contract has been signed yet," Musk tweeted late Monday.

"The Hertz agreement has no bearing on our profitability."Elon Musk: 'I really didn't want to be CEO of Tesla'

A request for comment from Tesla and Hertz was not immediately returned.

Last week, Interim Hertz Chief Executive Officer Mark Fields told a major Newswire that the order will mostly consist of Model 3 cars. Given that Tesla's cheapest Model 3 car starts at around $44,000, the full order could be worth over $4.4 billion if it were all for the mass-market sedan.

"Because there is considerably more demand than supply at Tesla," Musk explained, "we will only sell cars to Hertz at the same margin as we will to consumers."