What happened

Shares of Maxeon Solar Technologies (MAXN -33.36%) have had their share of ups and downs -- but mostly downs -- since the company's widely publicized spinoff from parent company SunPower in late August.

On spinoff day, Maxeon shares closed at $19, but by late September, they had lost more than a third of their value. As recently as Monday, Maxeon appeared to be back on an uptrend, and was approaching $22 a share -- but today, it no longer looks like the stock is going to get there after all.

Maxeon stock is down 12.2% as of 11 a.m. EDT -- and Goldman Sachs is to blame.

Cartoon characters confused by stock chart arrow falling and crashing into floor

Image source: Getty Images.

So what

The famed investment banker downgraded shares of Maxeon Solar from neutral to sell last night, and slapped a price target of only $15 on the stock -- well below what Maxeon stock sold for immediately following its spinoff, and approaching the lowest price the stock has fetched in the last two months.  

Although Goldman Sachs remains positive on the solar industry in general, both "in the U.S. and abroad," notes StreetInsider.com, the analyst has "margin/pricing/FCF concerns" regarding individual players within the solar industry, and regarding Maxeon in particular.

Now what

Goldman notes that one of its biggest concerns is Maxeon's Hemlock Semiconductor business, which depends largely on Chinese solar companies' demand for its product, and which has been hurt by tariffs China imposed on polysilicon imports during the U.S.-China trade war. Goldman also cites weak prices resulting from what analysts call "massive government subsidies" for its own polysilicon suppliers.  

Goldman is recommending investors sidestep these concerns and buy shares of thin-film solar specialist First Solar or the more profitable Canadian Solar instead.