What happened

After rising more than 4% in November, shares of Enphase Energy (ENPH -2.17%) found themselves considerably less desirable among investors in December -- a month in which the stock fell 17.4%, according to data provided by S&P Global Market Intelligence.

In addition to an analyst's downgrade on Enphase's stock, insider selling motivated investors to exit their positions in the last month of trading before the new year.

So what

While Enphase traded flat for the first couple of weeks in December, the bears started growling on Dec. 15, when Biju Perincheril, an analyst at Susquehanna, downgraded the stock to neutral from positive and assigned it a price target of $365. According to TheFly.com, Perincheril predicated the stock's downgrade on the belief that it had reached a "relatively rich valuation" and was "now priced for near perfection."

Oftentimes, when those in the C-suite sell shares in the companies they lead, investors take note. And that's exactly what played out last month. In a regulatory filing, Enphase reported on Dec. 13 that CEO Badri Kothandaraman sold 82,347 shares, netting himself about $26.1 million. Days later, investors learned that the selling spree for Kothandaraman continued. On Dec. 16, a regulatory filing revealed that he sold 36,327 shares for about $11.9 million.

In other insider-selling news, Jeff McNeil, the chief operating officer, also reported that he trimmed his position. On Dec. 15, McNeil reported that he sold 15,000 shares for about $4.9 million.

Now what

As for Perincheril's downgrade of Enphase stock, it's crucial for investors to remember that an analyst's opinion is merely one data point. While it's certainly worth noting the individual perspective, it's important to also recognize that there were several analysts who offered bullish takes on the stock in December. An analyst at Piper Sandler, for example, revealed an overweight rating on Enphase's stock on Dec. 22 and hiked the price target to $350 from $300.

As for the insider selling, there are various reasons a member of a company's leadership team might sell shares; it's not merely a reflection of a bearish opinion on the stock. Therefore, investors shouldn't singularly interpret the transaction as a harbinger of worse things for the stock.

A leader in microninverter technology, Enphase has made strides in expanding into energy storage and other niches of the renewable energy industry, making it a compelling option for green-energy investors. Nothing that happened in December changes that fact.