What happened

Shares of TuSimple (TSP), which develops self-driving technology for long-haul trucks, jumped 8% on Tuesday bringing their two-day gain to 25.3% after Monday's pop of 16%. This marks two consecutive days of the stock setting a new high. 

Investors seem enthused about the prospects for the newly public company, which held its initial public offering (IPO) on April 15. The stock IPOed at $40 and closed at $70.55 on Tuesday, so it's up 76.4% since it began trading two and a half months ago.  

For context, the S&P 500 was up just 0.6% in the first two days of this week.

Several white-colored tractor trailers traveling on a highway in a rural area.

Image source: Getty Images.

So what

TuSimple didn't release any news on Monday or Tuesday, nor did there seem to be any Wall Street analyst upgrades.

Furthermore, it seems that we can probably rule out the stock being one of the ever-growing number of "meme stocks" -- stocks with high short interest that individual investors following certain Reddit communities are pouring into.

Only 4.4% of TuSimple's float (shares available for trading) and 2.9% of its total shares were sold short as of June 15, the latest available data. Moreover, while trading volume was higher than usual on Tuesday, it wasn't overly high, and Monday's volume was only about average.

So, we can probably conclude that the 25% surge in TuSimple stock over the last two days is being primarily driven by some combination of more individual investors discovering the newly public company and buying shares and new institutional buying.

It's worth noting that tech giant NVIDIA (NVDA 3.51%) was a pre-IPO investor in TuSimple and popular stock picker Cathie Wood has bought shares for a couple of her ARK Invest exchange-traded funds (ETFs).

Now what

I'll conclude as I did in my recent deep dive into TuSimple, "TuSimple stock deserves a place on the watchlists of growth investors who are comfortable with companies that aren't yet profitable. The company operates in a space with gargantuan growth potential, has many top-tier partners and investors, and has a hefty cash position."