A few years back, amid one of Tesla's periodic stock rallies, I suggested that shares could hit $400.

Didn't happen! The stock retreated and, until quite recently, failed to threaten that mark again.

But this week, Tesla surged through $400, an over-60%-improvement since September. The rally started when the company reported a surprise profit for the third quarter. And yet again, Tesla's market cap is the biggest of any US automaker (at better than $70 billion, Tesla has a big lead on No. 2 General Motors' $50 billion).

It remains to be seen whether Tesla shares remain at this level, testing that $400 mark, or whether they plunge or climb still higher. With the fourth quarter nearly wrapped, analysts expect another profit, so the stage is set for the rally to extend early next year.

Volatility has always defined Tesla trading, but this rally has been a pretty smooth ascent. Could the era of wild swings in Tesla's stock price be coming to an end?

Let's dig into some charts:

Read more:

These charts show how the era of rampant Tesla stock volatility could be coming to an end - Business Insider