What happened

Tesla (TSLA 12.06%) will hold its long-awaited Battery Day presentation just five days from now, on Sept. 22. With the date so close, you might expect investors would be starting to get excited to hear what the world's most famous electric car manufacturer will say. But in fact, the opposite seems to be true.

Tesla stock plunged 7.6% in very early trading this morning, and as of 9:55 a.m. EDT, shares remained down 3.9%.

Glowing red stock chart arrow trending down

Image source: Getty Images.

So what

Presumably, the broad-based sell-off in tech stocks this morning (the Nasdaq was down 1.5%) has something to do with it. But the Battery Day preview that analysts at Baird just released may also be giving investors cause for concern.

In an exercise in guesswork related by StreetInsider.com this morning, Baird predicts that when Tesla pulls the veil off its Battery Day plans, it might reveal any of (a) a new low-cost cell, (b) a "significant" increase in battery production capacity, or (c) deeper moves into stationary energy-storage management for homeowners and utilities.

Or perhaps (d) all of the above.

Now what

Also, a new Tera battery factory in Fremont, California, is reportedly working on a battery twice the diameter of its current automotive battery cells, and Tesla has patent applications for a new, denser battery. You might think that either of these developments, along with Baird's predictions, would excite Tesla investors in the run-up to Battery Day.

The problem is, Baird itself does not seem excited by any of the above. After musing publicly on all the things Tesla might reveal to us next week, the analyst concluded by rating the stock only neutral, and with a $332 price target that implies a 23% downside.