The dog days of summer are barking, and they're scaring off investors from Nano Nuclear Energy (NNE 0.19%) stock this week. After an inauspicious start to the week, shares of the nuclear energy stock recovered slightly -- very slightly -- on Thursday, stemming the downward trend that they had been on from Monday through Wednesday.

According to data provided by S&P Global Market Intelligence, shares of Nano Nuclear Energy have plunged 18.9% from the end of last Friday's trading session through the market's close on Thursday.

An atom against a multicolored background.

Image source: Getty Images.

A case of the "Mondays" that lasted through Wednesday

Nano Nuclear Energy stock started the week on a sour note after Ladenburg analyst Michael Legg downgraded the stock to sell and slashed the price target to $9. Legg's actions are a stark turnaround from July, when Ladenburg initiated coverage on Nano Nuclear Energy stock with a buy rating and a $51 price target.

The bearish outlook that Ladenburg shared on Monday for the nuclear energy stock had a significant effect on investors, who continued to sell shares through Wednesday.

But Thursday brought a reprieve to the sell-off. Nano Nuclear Energy reported that the company had advanced to the final round of the pitch event for the U.S. Army xTechSearch 9 competition. The is a competitive initiative led by the U.S. Army's xTech program that fosters engagement with sophisticated technology companies to explore solutions for critical defense applications.

Does the stock's drop represent a buying opportunity?

While Ladenburg's outlook on Nano Nuclear Energy is inspiring a sell-off this week, investors should remember that analysts have shorter investing horizons in mind when they issue price targets, making them of less concern for patient investors who intend to hold on to their shares for at least several years. With respect to the news with U.S. Army, it's worth noting, but it does little to change the investment thesis for the company.

If you were bullish on Nano Nuclear Energy stock last week, nothing developed this week that should change your mind.