What happened

The Nasdaq composite index spent most of Wednesday in the red, but things really started melting down around 1:30 p.m. EDT, and the index closed the day down 3%.

Electric vehicle (EV) stocks suffering some of the greatest damage, with Chinese EV company Kandi Technologies (NASDAQ:KNDI) crashing 9.6% and Spartan Energy Acquisition (NYSE:SPAQ), which aims to bring Fisker public, falling 10.6%. Kensington Capital Acquisition (NYSE:KCAC), which will take the Bill Gates-backed lithium-battery maker QuantumScape public in a reverse-merger IPO, collapsed 11.8%.

3 colorful arrows all pointing down

Image source: Getty Images.

So what

Tesla (NASDAQ:TSLA) may have had a role in all this. For months, the company has hyped its Battery Day event as the platform to announce transformative improvements in the technology of EV batteries, including, perhaps, a much-touted "million-mile battery." As it turned out, however, when Battery Day rolled around last night, most of Tesla's promises involved incremental battery improvements (along with the resulting price and range improvements for EVs) that are up to 10 years in the future.

Now what

Some of Tesla's revelations were quite intriguing: Elon Musk's observation, for example, that there is enough lithium under the State of Nevada alone to replace every one of America's 300 million gas-guzzling cars with an EV, which seems to put the lie to the idea that there's a deficit of lithium in the world today.

I also liked Musk's step-by-step tutorial in how rechargeable batteries are made -- and how Tesla has rethought the process to invent a brand-new battery that's perhaps shorter and stubbier than the batteries we've all come to know and love, but dramatically more efficient and powerful, and cheaper to produce. That bodes well for Tesla taking its recent run of profitable earnings quarters (now at four in a row) and extending them even further into the future.

Still, it seems most investors were hoping for something more from the Tesla CEO. When they didn't get it, they started a sell-off that drove Tesla stock down more than 10% by day's end, taking the rest of the EV industry with it.