Despite a seemingly neverending surge in popularity, a new market study shows that the growth of craft beer sales appears to be slowing. According to market research firm IRI worldwide, craft brew sales are so far up only 6.5 percent year-to-date through May 15, down from more than 17 percent gains last year.

However, pouring a few certain companies out reveals a different trend.

Brewers Association chief economist Bart Watson took to Twitter to point out that if non-Brewers Association companies such as Blue Moon and Shock Top are taken out of the equation, craft growth goes up almost 9 percent. IRI includes them in their numbers, where the Brewers Association does not, given that Blue Moon is owned by Coors and Shock Top by Anheuser.

New IRI data has craft up “only” 6.5% YTD by volume. But take out Blue Moon (-4%) & Shock Top (-9%) and growth goes up to 8.9%. — Bart Watson (@BrewersStats) May 26, 2016

In an interview with drinks site Brewbound, Watson said the big brewery-caused deflation is even more prominent.

Large craft brewing companies that are do qualify for the Brewers Association definition, such as Yuengling, Boston Beer, New Belgium and Sierra Nevada, are all down a combined 4 percent. This surprising data could point to a shift from consumers drinking larger regional breweries and focusing more on their smaller locals.

“I don’t think IRI has Yuengling in their craft, but the other three are 33.9 percent of IRI’s craft cases right now,” said Watson. “Add in Blue Moon and Shock Top and you’re looking at 48 percent of IRI ‘craft,’ which is down 8 percent in the last four weeks. That’s going to pull hard on any number.”

Conversely, as Watson tweets, Brewers Association-certified craft is actually up 10.4 percent in IRI’s scan of the industry.

If I’m pulling it correctly – I get BA craft up 10.4% in IRI scan data YTD through 5-15-16. — Bart Watson (@BrewersStats) May 26, 2016

So in summary, smaller craft brews are selling fine, while venerable companies such as Sierra Nevada and New Belgium are seeing signs of a troubling future. As you drink in this info, consider revisiting our feature on the future of craft beer.