Is It Time to Buy the S&P 500's 3 Worst-Performing October Stocks?

Down in October. Up in November. That's been the story of the S&P 500 over the last couple of months. And where the index goes, so goes many of its component stocks.

A handful of S&P 500 members delivered especially horrible losses last month. But they've all rebounded at least somewhat off of their lows. Is it time to buy the S&P 500's three worst-performing October stocks?

1. SolarEdge Technologies

SolarEdge Technologies (SEDG 2.81%) earned the dubious distinction of being the worst S&P 500 stock last month. Shares of the solar-energy systems maker plunged 41% in October after announcing preliminary third-quarter results on Oct. 19 that were well below expectations.

The company reported its actual Q3 results on Nov. 1, confirming just how disappointing its latest quarter was. SolarEdge's revenue of $725 million wasn't anywhere close to the previous guidance range of $880 million to $920 million. This shortfall also impacted the company's bottom line, with SolarEdge posting a net loss in Q3 of $61 million.

SolarEdge CEO Zvi Lando said in the Q3 update that the solar energy systems market is slowing, especially in Europe. As a result, the company also expects significantly lower revenue in Q4.

While SolarEdge stock has bounced back a little in November, it remains far below the levels from earlier this year. Does this present a great buying opportunity for long-term investors? I don't think so.

The problem is that there's no way to know for sure how long the industry slump will last. Meanwhile, SolarEdge's valuation doesn't look very attractive, even with its steep decline.

2. Align Technology

Align Technology (ALGN -0.48%) ranked among the worst S&P 500 stocks in September. It made a repeat appearance on the list in October, with shares of the orthodontic-device maker plummeting nearly 40%.

Investors didn't like Align's Q3 results announced last month. The company missed Wall Street's top- and bottom-line estimates. Align also lowered its full-year 2023 revenue guidance, citing "a more challenging macroeconomic environment for doctors and patients with fewer orthodontic case starts overall."

Align's share price has rebounded nicely so far in November. It still has a long climb to get back to its previous highs. However, I like that the company plans to accelerate $250 million in stock buybacks. Align Technology CEO Joe Hogan revealed that he is personally buying another $1 million of the stock, as well.

Those are strong signs that Align's board and management team remain optimistic about the company's long-term prospects. I think that confidence is warranted. Align looks like a good stock to buy on the pullback, in my view.

3. Enphase Energy

October just wasn't a great month for solar-energy stocks. Enphase Energy (ENPH 3.80%) joined SolarEdge as one of the three worst performers last month, with its shares sinking nearly 34%.

Enphase's first sell-off in October was a direct result of SolarEdge's disappointing Q3 sneak peek. The stock fell even more later in the month when it disappointed investors on its own. Although Enphase's Q3 earnings beat analysts' estimates, its sales fell short.

More importantly, Enphase issued Q4 revenue guidance that was much lower than the company's sales generated in the prior-year period. Like SolarEdge, Enphase pointed to weaker demand in key European markets.

I think that the same argument against buying SolarEdge stock also applies to Enphase. There's uncertainty about how long the current industry headwinds will continue.

Enphase stock's valuation isn't compelling enough to justify buying right now. Investors can find better opportunities.