Shares in Glanbia have fallen almost 12 per cent in the past 24 hours after Bank of America analysts gave a negative view of the nutrition group’s stock amid a challenging global whey protein market and a potential reversal in the “proteinmaxxing” trend.

In an analysis note issued Thursday morning, Bank of America said currently elevated whey prices were “a net positive” for Glanbia because of its “superior supply chain”.

However, analysts said whey price levels were “unsustainable” and would reverse as more supply hit the market over the coming months.

The bank said it expected production to be 20 per cent higher in the 2026-2027 financial year because “elevated prices and demand have sparked [capital expenditure] programmes across the industry”.

On the demand side, Glanbia has benefited from the rise in popularity of weight-loss drugs globally. Users of these GLP-1s are advised to increase protein intake to help preserve muscle mass while losing weight, and Glanbia is among the bigger suppliers of protein products globally.

“GLP is definitely a tailwind,” Glanbia’s chief executive Hugh McGuire said last month after the group reported a 7 per cent jump in revenue for the first six months of the year, which included a 25 per cent spike in demand for its premium protein powder product, Optimum Nutrition.

However, the bank said it could not rule out the so-called proteinmaxxing trend “starting to come down”, amid “protein marketing fatigue, with a switch toward other ingredients like fibre, creatine or even peptide”.

Rating the stock “underperform”, the analysts said increased supply of whey could collide with lower demand over the coming year, which would have a direct impact on Glanbia’s dairy nutrition division’s profit expectations.

Glanbia’s share price fell 7.5 per cent in Dublin on Thursday, closing at €19.93, before sliding another 5.4 per cent by lunchtime on Friday.

Last month the Dublin-listed group lifted its earnings forecast for the year after reporting the better-than-expected half-year results. In its health and nutrition sector, revenues rose almost 18 per cent year on year, reaching $368.5 million, while income in the dairy nutrition division rose 3.9 per cent to $793.7 million.

Following the “strong performance”, Glanbia said it now expected to deliver adjusted EPS (earnings per share) growth of 17-20 per cent for 2026, an upgrade on the previous forecast of 7-11 per cent.