Billionaire entrepreneur Elon Musk took the Twitter route late Tuesday to dismiss reports that said Tesla Motors was in talks with Samsung SDI to supply batteries for its upcoming “affordable” sedan, the Model 3. Musk said his company was “working exclusively with Panasonic” for the batteries.

Minutes later, referring to the Model S sedan and Model X SUV, he added:

In April, Musk said Tesla would increase total vehicle production to 500,000 units in 2018, a goal suppliers have said would be difficult to achieve. The company has already taken 373,000 orders for Model 3. Reports cited anonymous sources Tuesday who said Tesla was likely to add Samsung SDI — a Samsung subsidiary independently listed on the South Korean stock exchange — as a supplier of batteries if sales of Model 3 exceeded expectations.

Samsung SDI declined to comment on the reports, but its shares climbed over 6 percent during trade Tuesday, beating the wider South Korean stock market that gained 0.93 percent. On Wednesday, however, the KOSPI Index gained 0.77 percent while, following Musk’s tweets, shares of Samsung SDI shed 8 percent. Shares of Panasonic, on the other hand, rose as much as 5 percent in response to the news Wednesday, before closing 3.68 percent higher on the Tokyo Stock Exchange, while the broader Nikkei 225 Index gained 0.93 percent.