TOKYO – It’s hard to decide who had a worse September 22, Elon Musk’s Tesla or Kazuhiro Tsuga’s Panasonic.

Musk’s stumble that day surely garnered the most headlines. Investors gave the thumbs down to his “Battery Day” presentation, which was bold on spin but hazy on how Tesla would make cheaper, mass-market cars in short order.

Tesla shares promptly lost their fizz, wiping out tens of billions of market value.

“While we applaud the company's ambitious plans, we believe it is an inherently risky move with steep execution and operational challenges,” says analyst Rajvindra Gill of Needham & Co.

Tsuga’s Panasonic took its own knocks in the market that day, courtesy of Tesla. Musk, it appears, is tossing a once-valued partner under the proverbial bus. His plans to focus on in-house battery production to save costs have Panasonic investors worried about the fate of Tesla’s longtime cell supplier.