Stocks have rallied in the last month on signs that the economy has thus far been resilient to tariffs and on hopes that the U.S. and China can negotiate a trade agreement. However, not every stock has been a winner.

Let's take a look at two of the worst-performing stocks on the S&P 500 (^GSPC -0.03%) over the last month to see if either of them is worth buying.

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1. Enphase Energy

Enphase Energy (ENPH 4.21%), a leading maker of microinverters used with solar panels, took a dive on Tuesday, as the Senate kept cuts to wind and solar energy incentives that were in the House version of the tax and budget bill.

Enphase was one of several solar stocks that tumbled on the news, falling 24%, and as of June 17, it's down 30.7% over the last month.

That performance continues a weak run for the stock, which is down over the last five years, as solar stocks have struggled due to competition from China, a volatile regulatory environment, and falling prices.

Enphase reported first-quarter earnings in April, with solid top-line growth of 35% to $356.1 million and a profit of $29.3 million. Nonetheless, an end of regulatory credits could put significant pressure on its business.

2. Brown-Forman

Brown-Forman (BF.B), maker of Jack Daniel's and other spirits, has also struggled due to regulatory challenges. In Brown-Forman's case, it's due to tariffs imposed on American whiskey exports, impacting its top brands, which also include Woodford Reserve. As of June 17, the stock was down 28.5% over the last month.

In its first-quarter earnings report, the company said that revenue fell 7%, or 3% on an organic basis.

Brown-Forman also said it named new distributors in 13 markets across the U.S., part of an effort to deliver a boost to domestic sales.

Still, with geopolitical pressure on American spirit brands, and broader weakness in the category, Brown-Forman seems likely to continue to struggle.