Topher Scott Millennials aren't drinking enough beer to keep brands afloat.

According to CNBC, Goldman Sachs downgraded both Boston Beer Company and Constellation Brand on the data that younger consumers aren't drinking as much alcohol as older generations, and the ones who do prefer wine and spirits.

"We view the shift in penetration and consumption trends as driven by a shift in preferences in the younger cohorts," Chief Analyst Freda Zhuo wrote.

Beer penetration fell 1% from 2016 to 2017 in the US market, while both wine and spirits were unmoved, according to Nielsen ratings.

Goldman Sachs now expects the overall beer market in the US to decline by 0.7% in 2017. It downgraded Boston Beer Company from "neutral" to "sell" and Constellation Brands from "buy" to "neutral."